- underline⇄noun 1. a line drawn or printed under a word or passage.
2. the line of the lower part of the body of an animal, especially a sheep. - underline⇄underline, verb, -lined,-lining,noun.
- underline⇄v.t. 1. to draw a line or lines under; underscore.
Ex. In writing, we underline titles of books.
2. (Figurative.) to make emphatic or more emphatic; emphasize.