Lipstick was a cosmetic product used primarily by females to apply a different color to their lips.
In 2371, Neelix observed that Captain Kathryn Janeway looked wonderful one morning while she was looking for coffee in his kitchen in the USS Voyager's mess hall. Neelix thought one of the things she changed about her look was that she might have applied a different color lipstick. Janeway responded that it was, in fact, the same color. (VOY: "The Cloud")