noun a small or narrow crescent.
2. lunule ·noun a lune. ·see lune.
3. lunule ·noun anything crescent-shaped; a crescent-shaped part or mark; a lunula, a lune.
4. lunule ·noun 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. ·see ·illust. of bivalve.