1. <anatomy> Anything crescent-shaped; a crescent-shaped part or mark; a lunula, a lune.

2. <chemistry> A lune. See Lune.

3. <zoology> A small or narrow crescent. A special area in front of the beak of many bivalve shells. It sometimes has the shape of a double crescent, but is oftener heart-shaped.

Origin: F, fr. L. Lunula, dim. Of luna moon.

(01 Mar 1998)