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[sef-uh-loh-thawr-aks, -thohr-] /ˌsɛf ə loʊˈθɔr æks, -ˈθoʊr-/
noun, plural cephalothoraxes, cephalothoraces
[sef-uh-loh-thawr-uh-seez, -thohr-] /ˌsɛf ə loʊˈθɔr əˌsiz, -ˈθoʊr-/ (Show IPA).
the anterior part of the body in certain arachnids and crustaceans, consisting of the coalesced head and thorax.
Origin of cephalothorax
1825-35; cephalo- + thorax
Related forms
[sef-uh-loh-thuh-ras-ik] /ˌsɛf ə loʊ θəˈræs ɪk/ (Show IPA),
adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for cephalothorax
  • Her cephalothorax lowers, he dances with the rising sun as if beckoning the light to share in this moment.
  • The abdomen is equal in length or a little longer than the cephalothorax.
  • Pupae do not have a distinct head and thorax, rather a composite structure called the cephalothorax.
  • They have five to seven pairs of legs, two pairs of antennae, and two body regions know as the cephalothorax and abdomen.
  • Spiders are characterized by having eight legs and the two distinct body regions of the cephalothorax and abdomen.
  • The head and part of the thorax are fused in a cephalothorax.
  • All spiders have two body parts-the cephalothorax and abdomen.
  • The spiders, mites and ticks have four pairs of legs on the cephalothorax and no abdominal appendages.
British Dictionary definitions for cephalothorax


noun (pl) -raxes, -races (-rəˌsiːz)
the anterior part of many crustaceans and some other arthropods consisting of a united head and thorax
Derived Forms
cephalothoracic (ˌsɛfələʊθəˈræsɪk) adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for cephalothorax

1829, from cephalo- + thorax. Perhaps from French or German.

Online Etymology Dictionary, © 2010 Douglas Harper
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cephalothorax in Science
The combined head and thorax of arachnids, such as spiders, and of many crustaceans, such as crabs.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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