Melanosis coli refers to the condition in which the lining of the colon turns brown or black due to accumulation of pigment. There are several other terms that may be used to describe this condition, such as pseudomelanosis coli, colonic melanosis, and colonic lipofuscinosis. The term pseudomelanosis coli is often used when the pigmentation is caused by the accumulation of iron sulfide rather than melanin. Colonic melanosis and colonic lipofuscinosis are used interchangeably with melanosis coli, as they both describe the same condition of pigmentation in the colon. While melanosis coli is generally a benign condition, it is associated with chronic laxative use and may be indicative of other colon disorders.