Cosmesis is the preservation, restoration, or bestowing of bodily beauty. In the medical context, it usually refers to the surgical correction of a disfiguring defect, or the cosmetic improvements made by a surgeon following incisions. Its usage is generally limited to the additional, usually minor, steps that the surgeon (who generally is operating for non-cosmetic indications) takes to improve the aesthetic appearance of the scars associated with the operation. Typical actions include removal of damaged tissue, mitigation of tension on the wound and/or using fine (thin) sutures to close the outer layer of skin.
Cosmetic surgery is the portion of plastic surgery that concerns itself with the elective improvement of cosmesis.
In relation to prosthetic limbs 
The practice of cosmesis, the creation of lifelike limbs made from silicone or PVC, has grown in popularity. Such prosthetics, such as artificial hands, can now be made to mimic the appearance of real limbs, complete with freckles, veins, hair, fingerprints and even tattoos. Custom-made cosmeses are generally more expensive (costing thousands of US dollars, depending on the level of detail), while standard cosmeses come ready-made in various sizes, though they are often not as realistic as their custom-made counterparts. Another option is the custom-made silicone cover, which can be made to match a person's skin tone but not details such as freckles or wrinkles. Cosmeses are attached to the body using an adhesive, suction, form-fitting, stretchable skin, or a skin sleeve.
- Dorland's Medical Dictionary. 25th ed. Philadelphia: W.B. Saunders Co.; 1995