Any of various marine arthropods of the class Merostomata, especially Limulus polyphemus or Xiphosura polyphemus of eastern North America, having a large rounded body and a stiff pointed tail. Also called king crab, limulus.
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.