1. The line of the lower part of the body (of an animal).
1886. C. Scott, Sheep-farming, 173. The back should be level and evenly covered with meat,… the underline straight.
1899. Jrnl. R. Agric. Soc., X. March, 18. Her [a cow’s] back and underline were nearly parallel, but she wanted hair and milk.
2. a. A line drawn below words printed or written. b. pl. A set of ruled guiding-lines placed under paper that is being written on.
1888. E. M. Gallaudet, Life T. M. Gallaudet, 23. It [a juvenile essay] is written on unruled paper, with a most careful regard for lines and margins, suggesting the use of underlines.
3. A line at the bottom of a play-bill announcing the piece to be performed next.
1891. Cent. Dict., s.v.
