[ sef-uh-loh-thawr-aks, -thohr- ]
/ ˌsɛf ə loʊˈθɔr æks, -ˈθoʊr- /

noun, plural ceph·a·lo·tho·rax·es, ceph·a·lo·tho·ra·ces [sef-uh-loh-thawr-uh-seez, -thohr-] /ˌsɛf ə loʊˈθɔr əˌsiz, -ˈθoʊr-/. Zoology.

the anterior part of the body in certain arachnids and crustaceans, consisting of the coalesced head and thorax.

Nearby words

  1. cephalopod,
  2. cephalosporin,
  3. cephalosporinase,
  4. cephalostat,
  5. cephalothoracic,
  6. cephalous,
  7. cephalus,
  8. cepheid,
  9. cepheid variable,
  10. cepheid variables

Origin of cephalothorax

First recorded in 1825–35; cephalo- + thorax

Related formsceph·a·lo·tho·rac·ic [sef-uh-loh-thuh-ras-ik] /ˌsɛf ə loʊ θəˈræs ɪk/, adjective

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for cephalothoracic


/ (ˌsɛfələʊˈθɔːræks) /

noun plural -raxes or -races (-rəˌsiːz)

the anterior part of many crustaceans and some other arthropods consisting of a united head and thorax
Derived Formscephalothoracic (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

Word Origin and History for cephalothoracic



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

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for cephalothoracic


[ sĕf′ə-lō-thə-răsĭk ]


Relating to the head and the chest.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for cephalothoracic


[ sĕf′ə-lə-thôrăks′ ]

The combined head and thorax of arachnids, such as spiders, and of many crustaceans, such as crabs.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.