Use scar in a sentence. LINK / CITE ADD TO WORD LIST. noun. A scar from knee surgery. A scar from knee surgery. The definition of a scar is a mark left on the skin after it heals, or a sign of mental or physical damage.1  An example of a scar is a line on a fingertip after a paper cut.2  An example of a scar is a dent on a car.se scar in a sentence. LINK / CITE ADD TO WORD LIST. noun. A scar from knee surgery. A scar from knee surgery. The definition of a scar is a mark left on the skin after it heals, or a sign of mental or physical damage.