verb (used with object), un·der·lined, un·der·lin·ing.
- to mark with a line or lines underneath; underscore.
- to indicate the importance of; emphasize, as by stressing or italicizing.
- Printing. a caption under an illustration.
- a line drawn under something; an underscore.
verb (ˌʌndəˈlaɪn) (tr)
- to put a line under
- to state forcibly; emphasize or reinforce
- a line underneath, esp under written matter
v.1721, from under + line (v.). Cf. Dutch onderlijnen. Related: Underlined; underlining. The noun is attested from 1888.