Words at Play : Words For Things You Didn't Know Have Names
Definition:
lunule : a crescent-shaped body part or marking (such as the whitish mark at the base of a fingernail)
Example Sentence:
He folded his hands together to give an impression of calm, but the ragged skin below his lunules told another story.
Origin:
This mark got its name because of its shape: lunule comes from the Latin luna, meaning "moon."