Medically reviewed by Dr Sin Yong · Last reviewed · 19 min read
Plain-language explanations of the terms used in aesthetic medicine — what they mean, and where they apply. Written by Dr Sin Yong, Orchard Road, Singapore.
4K Body Lift is Dr Sin Yong's high-definition body-sculpting protocol on the Secret Duo radiofrequency platform. It is radiofrequency only, does not use EMS or electromagnetic muscle stimulation, and is planned around the fat compartments addressed in liposuction without incision or anaesthetic. Learn more →
An ablative laser is a laser that vaporises the outer layers of skin to prompt renewal and collagen remodelling. Carbon dioxide (CO2) and erbium:YAG lasers are the main examples. Because the surface is removed, these lasers generally involve more recovery and aftercare than non-ablative approaches, and settings are adjusted for darker skin types. Learn more →
Androgenetic alopecia is the most common type of hair loss, also called male or female pattern hair loss. It is driven by genetic sensitivity of hair follicles to androgens, which makes them shrink over time. In men it often affects the hairline and crown; in women it usually causes diffuse thinning at the parting. Learn more →
An atrophic scar is a depressed scar that sits below the surrounding skin because collagen was lost during healing, most often after acne or chickenpox. Atrophic acne scars are classified as ice pick, boxcar or rolling, and each type responds to different techniques, so most plans combine several. Learn more →
A biostimulator is an injectable that prompts the body to produce its own collagen over time, improving firmness and volume gradually rather than immediately. Common examples are poly-L-lactic acid, calcium hydroxylapatite, polycaprolactone and poly-D,L-lactic acid. Biostimulators are not dissolved by hyaluronidase, so assessment and technique matter. Learn more →
Blepharoplasty is surgical correction of the eyelids, which removes or repositions excess skin, fat or muscle in the upper or lower lids. It is the surgical option for hooded upper lids and eye bags. Some energy-based lifting treatments are used as a non-surgical alternative where the degree of change suits them. Learn more →
Body contouring refers to non-surgical treatments that refine body shape, reduce localised fat or firm loose skin in areas such as the abdomen, flanks, arms and thighs. It is distinct from weight loss: it is suited to people near a stable weight who want to address specific areas. Learn more →
Botulinum toxin is a prescription-only medicine that temporarily reduces muscle activity by blocking the nerve signals that make muscles contract. In aesthetic medicine it is used to soften expression lines, slim enlarged jaw muscles and reduce excessive sweating. Effects wear off over months as nerve signalling recovers. Learn more →
Boxcar scars are acne scars with sharply defined, vertical walls and a flat base, giving a box-like depression in the skin. They may be shallow or deep, and their edges catch light and cast shadow. Treatment usually aims to soften the walls and raise the base, often with fractional resurfacing. Learn more →
Calcium hydroxylapatite is a biostimulator made of microspheres of a mineral naturally found in bone, suspended in a gel carrier. It gives some immediate lift from the gel and then stimulates collagen around the microspheres. Diluted forms are used for skin quality. Radiesse is a widely known brand. Learn more →
Collagen stimulation is the process by which a treatment prompts the skin to produce new collagen, the structural protein that gives skin firmness. Heat from lasers, radiofrequency or ultrasound, controlled micro-injury, and some injectables can all trigger it. Change builds gradually over weeks to months as new collagen matures. Learn more →
A collagen-stimulating filler is an injectable, such as poly-L-lactic acid, calcium hydroxylapatite or polycaprolactone, that works mainly by prompting the body to build its own collagen rather than by adding volume directly. Results develop gradually. These products are not reversed by hyaluronidase, so placement and dosing are planned carefully. Learn more →
Cryolipolysis, also called fat freezing, is a non-surgical treatment that cools localised fat to a controlled temperature, injuring fat cells while sparing the skin. The affected fat cells are cleared by the body over the following weeks to months. It is used for stubborn pockets, not for weight loss. Learn more →
A dermal filler is an injectable gel used to restore volume, support structure or refine contour in areas such as the cheeks, chin, temples and lips. Hyaluronic acid (HA) fillers can be dissolved with hyaluronidase if needed; non-HA fillers, such as calcium hydroxylapatite or poly-L-lactic acid, cannot. Learn more →
Diastasis recti is a separation of the two vertical abdominal muscles along the midline, most commonly after pregnancy. It can cause a bulge or doming in the tummy. It is a muscular and connective-tissue issue, which is different from loose skin or excess fat, and is assessed separately. Learn more →
Downtime is the period after a treatment during which visible effects such as redness, swelling, bruising or flaking may be present before the skin returns to its normal appearance. It varies with the treatment, the settings used and the individual, and is discussed at consultation so plans fit around work and events.
An erbium glass laser is a non-ablative fractional laser at 1540 nm, a wavelength absorbed by water in the dermis. It creates columns of heating beneath an intact surface to stimulate collagen, so it is used for acne scars, texture and fine lines, generally with shorter recovery than ablative lasers. Learn more →
The Fitzpatrick skin type is a six-point classification of skin according to how it responds to sun, from type I (always burns, never tans) to type VI (deeply pigmented, rarely burns). It helps doctors choose laser settings and anticipate the risk of post-inflammatory hyperpigmentation, which is higher in darker types.
A fractional CO2 laser is an ablative laser at 10,600 nm that vaporises microscopic columns of skin while leaving surrounding tissue intact. The healing response remodels collagen, so it is used for acne scars, surgical scars, texture and photoaging. Recovery involves several days of redness and crusting, depending on settings. Learn more →
A fractional laser is a laser that treats the skin in microscopic columns rather than across the whole surface, leaving untreated skin between each column. That untreated skin supports faster healing. Fractional delivery can be ablative, such as fractional CO2, or non-ablative, such as 1540 nm erbium glass. Learn more →
FSX Laser, also called the Flawless Smooth Skin laser, is Dr Sin Yong's combination laser skin protocol using 1540 nm and 1927 nm wavelengths: the 1540 nm wavelength reaches the dermis for collagen work, while 1927 nm acts more superficially, where pigment and surface texture sit. Learn more →
HIFU is focused ultrasound energy delivered to precise depths beneath the skin surface, including the SMAS layer, where it creates small points of heating. These prompt a collagen response that can firm and tighten tissue over the following months without incisions. Depth, energy and the number of lines are chosen for each area at assessment. Learn more →
Hyaluronic acid is a sugar molecule found naturally in skin, where it binds water and helps keep tissue hydrated and supple. In aesthetic medicine it is used in cross-linked form in dermal fillers and in lighter form in skin boosters. HA-based products can be broken down with the enzyme hyaluronidase. Learn more →
A hyaluronic acid filler is a dermal filler made of cross-linked hyaluronic acid gel. Different products vary in firmness and spread, so softer gels suit lips and fine lines while firmer gels support cheeks, chin and jawline. HA fillers are gradually broken down by the body and can be dissolved with hyaluronidase. Learn more →
Hyaluronidase is an enzyme used to break down hyaluronic acid filler, for example to correct overfilling, migration or lumps, and urgently in suspected vascular occlusion. It is a prescription medicine given by injection. It does not dissolve non-HA fillers such as Ellansé (polycaprolactone) or Sculptra (poly-L-lactic acid). Learn more →
A hypertrophic scar is a raised, thickened scar that stays within the boundary of the original wound. It usually appears within weeks of injury or surgery and often flattens gradually over months to years. Unlike a keloid, it does not spread into surrounding skin and is less likely to recur. Learn more →
Ice pick scars are narrow, deep acne scars that extend into the dermis like a small puncture, usually under two millimetres wide at the surface. Because they are deep and narrow, they respond to depth-focused techniques such as TCA CROSS or focused fractional laser rather than to treatments that work only on the surface. Learn more →
Intense pulsed light is a broad-spectrum light device, not a laser, that uses filters to target pigment and blood vessels. It is used for sun spots, redness, broken capillaries and photoaging. Because it treats several targets at once, careful settings are needed for darker skin types and for melasma.
Jowls are sagging soft tissue along the lower face and jawline that blurs the jaw's definition. They result from a combination of skin laxity, descent of fat compartments and weakening of supporting ligaments. Some jowls are mostly loose tissue and some are mostly fat, which changes how they are approached. Learn more →
A keloid is a raised, firm scar that grows beyond the boundary of the original wound, caused by excessive collagen production during healing. Keloids are more common on the chest, shoulders and earlobes, and in people with darker skin or a family history. They can itch or hurt and tend to recur after treatment. Learn more →
A key opinion leader is a doctor recognised by device manufacturers for clinical expertise with their platforms, who is invited to share that clinical expertise with other physicians and to speak at meetings and workshops. Dr Sin Yong is a KOL for several device companies, including CLASSYS, DEKA and Fotona. Learn more →
Laser toning is a technique using a nanosecond or picosecond laser at low energy, often 1064 nm Nd:YAG, passed over the skin in multiple sessions. It gradually breaks down excess pigment and evens tone with minimal surface disruption. It is used for melasma and dullness, with conservative settings to avoid rebound pigmentation. Learn more →
LDM (local dynamic micro-massage) ultrasound is a skin treatment that alternates between two ultrasound frequencies to create a rapid micro-massage effect within the tissue. It is used to support hydration, calm sensitivity and aid recovery after other procedures. It does not involve injections and is generally comfortable. Learn more →
The malar fat pad is a compartment of superficial fat over the cheekbone that gives the mid-face its fullness. With age it thins and descends, which flattens the upper cheek and deepens the nasolabial fold and tear trough. Restoring support here is often part of mid-face rejuvenation. Learn more →
Melasma is a chronic pigmentation condition causing symmetrical brown or grey-brown patches, most often on the cheeks, forehead and upper lip. It is influenced by hormones, sunlight, visible light and heat, and is more common in women with medium to darker skin. It tends to recur, so management is long-term. Learn more →
Microwave fat reduction is a body-contouring method that uses microwave energy to heat subcutaneous fat selectively while the skin surface is cooled. The heat damages fat cells, which the body then clears gradually, and can also tighten the overlying skin. Onda Coolwaves is one example of this technology. Learn more →
Monopolar radiofrequency is a form of radiofrequency in which energy flows from a single treatment tip to a return pad placed elsewhere on the body. This lets heat spread volumetrically through the dermis and deeper fibrous tissue, prompting collagen contraction and remodelling. Thermage and Volnewmer are examples of monopolar platforms. Learn more →
Nasolabial folds are the lines running from the sides of the nose to the corners of the mouth. Everyone has them, but they deepen as the mid-face loses volume and its soft tissue descends. Treatment usually looks at cheek support and skin quality rather than filling the fold alone. Learn more →
A non-ablative laser is a laser that heats the deeper skin to stimulate collagen while leaving the surface layer largely intact. Examples include 1540 nm erbium glass and 1064 nm Nd:YAG. Recovery is generally shorter than with ablative lasers, although a course of sessions is usually needed for gradual change. Learn more →
PDRN (polydeoxyribonucleotide) and polynucleotides are purified DNA fragments, usually derived from salmon, used in injectable skin treatments. They are thought to support tissue repair and hydration by providing building blocks for cell renewal and reducing inflammation. Rejuran is a well-known polynucleotide product used for skin quality. Learn more →
Photoaging is premature ageing of the skin caused by long-term ultraviolet and visible-light exposure, separate from natural chronological ageing. Signs include fine and coarse wrinkles, uneven pigmentation, sun spots, broken capillaries, roughness and loss of elasticity. Daily sun protection is the foundation of prevention and treatment. Learn more →
A picosecond laser is a laser that delivers energy in pulses lasting trillionths of a second. The very short pulse breaks pigment into fine particles mainly through a pressure effect rather than heat. It is used for pigmentation, tattoo removal and skin rejuvenation, and is often used at low energy for toning. Learn more →
Pillow face is an over-filled, rounded appearance that can develop when too much filler is placed over time, especially in the mid-face. It blunts natural facial contours and can make the face look heavier. Assessment looks at which product was used, where it sits, and whether dissolving or rebalancing is appropriate. Learn more →
Poly-L-lactic acid is a biodegradable, biocompatible polymer used as an injectable biostimulator. Injected in a course of sessions, it prompts a gradual collagen response that restores volume and firmness over months rather than immediately. The particles are slowly broken down by the body. Sculptra is a widely known example. Learn more →
Polycaprolactone is a biodegradable polymer used in injectable biostimulators and in some dissolvable threads. As a filler, PCL microspheres in a gel carrier give initial volume and then stimulate collagen as the gel is absorbed. Ellansé is a widely known PCL filler. It is not dissolved by hyaluronidase. Learn more →
Post-inflammatory erythema is lingering pink or red marks after acne, caused by dilated or damaged small blood vessels rather than by pigment. It is more noticeable in lighter skin and blanches when pressed. Because it is vascular, it responds to different treatments from brown post-inflammatory hyperpigmentation. Learn more →
Post-inflammatory hyperpigmentation is darkening of the skin that follows inflammation or injury, such as acne, eczema, insect bites or an over-aggressive treatment. It is more common and longer-lasting in darker skin types. It usually fades with time, sun protection and treatment of the underlying inflammation. Learn more →
A Q-switched laser is a laser that releases very high-energy pulses lasting billionths of a second (nanoseconds), designed to shatter pigment particles in the skin. Q-switched Nd:YAG at 1064 nm and 532 nm is widely used for pigmentation and tattoos, and at low fluence for laser toning. Learn more →
Radiofrequency is electrical energy that warms the deeper layers of the skin through resistance in the tissue, rather than through light. The controlled heat stimulates the body's own collagen production, so it is used for firming and tightening on both the face and body. Monopolar, bipolar and microneedle delivery reach different depths. Learn more →
Regenera Activa is an autologous micrografting technique for hair thinning. A few small samples of the patient's own scalp tissue are taken and mechanically processed into a suspension of cells and growth factors, which is then injected into thinning areas in the same session. It is performed under local anaesthetic. Learn more →
RF microneedling is a treatment that combines fine insulated or non-insulated needles with radiofrequency energy, releasing heat directly into the dermis at a chosen depth. The combined micro-injury and heat prompt remodelling of scar tissue and new collagen, so it is used for acne scars, enlarged pores, texture and mild laxity. Learn more →
Rolling scars are broad, shallow acne scars with sloping edges that give the skin an undulating, wave-like appearance. They are usually caused by fibrous bands tethering the skin to deeper tissue, which is why releasing those bands with subcision, alongside collagen-stimulating treatment, is a common part of the plan. Learn more →
S3 Resurfacing Lift is Dr Sin Yong's multi-depth acne scar protocol on the DEKA Tetra Pro fractional CO2 platform. The method is matched to each scar type — ice pick, boxcar and rolling — and it is also used for scars that did not fully respond to earlier CO2 laser or RF microneedling. Learn more →
A skin booster is an injectable treatment placed in fine droplets into the superficial skin to improve hydration, texture and elasticity rather than to change contour. Products include lightly cross-linked or non-cross-linked hyaluronic acid, polynucleotides and some biostimulators. A course of sessions is usually recommended. Learn more →
Skin laxity is looseness or reduced firmness of the skin, caused mainly by the gradual decline of collagen and elastin with age, sun exposure and weight change. It differs from volume loss, although the two often occur together. Mild to moderate laxity is commonly addressed with energy-based tightening treatments. Learn more →
The SMAS, or superficial musculoaponeurotic system, is a layer of fibrous connective tissue beneath the facial skin and fat that links the facial muscles. Surgical facelifts reposition this layer, and some energy-based treatments, such as focused ultrasound, are designed to deliver heat at its depth. Learn more →
A solar lentigo, often called a sun spot or age spot, is a flat, well-defined brown patch caused by cumulative ultraviolet exposure. Solar lentigines appear on sun-exposed areas such as the face, hands and forearms. They are harmless, but any changing or irregular spot should be examined by a doctor. Learn more →
Subcision is a technique that releases the fibrous bands tethering a depressed scar to the tissue beneath. A fine needle or cannula is passed under the scar to cut these bands, allowing the surface to lift. It is mainly used for rolling acne scars and is often combined with resurfacing or volume-restoring treatments. Learn more →
Submental fullness, often called a double chin, is excess fullness under the chin and jawline. It may come from fat, loose skin, muscle bands, chin projection or genetics, often in combination. Identifying the main cause guides whether fat reduction, skin tightening or chin support is appropriate. Learn more →
TCA CROSS (chemical reconstruction of skin scars) is a technique in which a high concentration of trichloroacetic acid is applied precisely into the base of individual atrophic scars, usually ice pick scars. The controlled injury prompts collagen to rebuild from the base, and several sessions spaced weeks apart are typically needed. Learn more →
The tear trough is the groove running from the inner corner of the eye down and outwards along the upper cheek. It becomes more visible with volume loss, thinning skin and bony changes, and can cast a shadow that looks like dark circles or tiredness. Filler here requires careful product choice and technique. Learn more →
Telogen effluvium is a temporary form of diffuse hair shedding in which more hairs than usual enter the resting (telogen) phase and fall out together, usually two to three months after a trigger. Triggers include illness, fever, childbirth, crash dieting, stress and some medicines. Most cases settle once the trigger resolves. Learn more →
A thread lift is a procedure in which dissolvable sutures, commonly made of polydioxanone (PDO) or polycaprolactone (PCL), are inserted under the skin to reposition soft tissue and stimulate collagen along their path. The threads are gradually absorbed. Threadless approaches aim for lift through stimulated tissue tightening instead. Learn more →
Time Freeze Laser LCLR® is Dr Sin Yong's dual-wavelength laser lifting protocol on a long-pulsed 755 nm and 1064 nm platform, working through controlled dermal heating. Together with VF Lift – Vertical Facelift, it is built to target Sculptra and Ellansé and take away the excess; not every laser can do this. Learn more →
Vaginal laxity is reduced firmness of the vaginal tissues, which some women notice after childbirth or with age and hormonal change. It may be associated with reduced sensation or mild urinary leakage. Energy-based treatments are one option discussed after a medical assessment of symptoms and history. Learn more →
Vascular occlusion is a rare but serious complication of filler injection in which product blocks or compresses a blood vessel, reducing blood supply to the skin or, very rarely, the eye. Warning signs include blanching, mottling and pain. It is treated urgently, including hyaluronidase for HA fillers. Learn more →
VF Lift – Vertical Facelift is a non-surgical lifting protocol developed by Dr Sin Yong on the CLASSYS Volnewmer 6.78 MHz monopolar radiofrequency platform, planned zone by zone along vertical vectors. It is radiofrequency only and does not use focused ultrasound (Ultraformer), and it is customised for both the face and the body. Learn more →
This glossary is general information, not medical advice. Suitability for any treatment is assessed individually at consultation.
“Most aesthetic confusion is two different treatments wearing the same marketing name.”
— Dr Sin Yong
Medically reviewed by Dr Sin Yong, MBBS (NUS), MRCS (Edinburgh) · Last updated 5 September 2026 · Editorial policy