1. burrowing crab of American coastal regions having one claw much enlarged in the male
The Collaborative International Dictionary of English v.0.48:
Fiddler \Fid"dler\, n. [AS. fi[eth]elere.]
1. One who plays on a fiddle or violin.
2. (Zool.) A burrowing crab of the genus Gelasimus, of many
species. The male has one claw very much enlarged, and
often holds it in a position similar to that in which a
musician holds a fiddle, hence the name; -- called also
fiddler crab, calling crab, soldier crab, and
3. (Zool.) The common European sandpiper (Tringoides
hypoleucus); -- so called because it continually
oscillates its body.
Fiddler crab. (Zool.) See Fiddler, n., 2.
WordNet (r) 3.0 (2006):
n 1: burrowing crab of American coastal regions having one claw
much enlarged in the male