stretch markstretch mark
a streak or wrinkle that forms in the skin, esp. of the abdomen, hips, or thighs, after the dermis has been stretched excessively in a short period of time due to pregnancy, obesity, etc.: usually used in pl.
A shiny line on the skin of the abdomen, breasts, thighs, or buttocks that is often lighter than the surrounding skin and is caused by the stretching and weakening of elastic tissues usually as a result of pregnancy or weight gain.