What is "labrums"

Labrum \La"brum\, n.; pl. L. Labra, E. Labrums. [L.]

1. A lip or edge, as of a basin.

2. (Zo["o]l.)

   1. An organ in insects and crustaceans covering the upper part of the mouth, and serving as an upper lip. See Illust. of Hymenoptera.

   2. The external margin of the aperture of a shell. See Univalve.