Main Entry: horseshoe crab

Function: noun

Date: 1797

: any of several closely related marine arthropods (order Xiphosura and class Merostomata) with a broad crescentic cephalothorax, six pairs of legs, and a spikelike tail; especially : one (Limulus polyphemus) of coastal waters from Maine to the Yucatán Peninsula —called also king crab