noun, plural tri·ceps·es [trahy-sep-siz] /ˈtraɪ sɛp sɪz/, tri·ceps. Anatomy.

a muscle having three heads or points of origin, especially the muscle on the back of the arm, the action of which straightens the elbow.

Nearby words

  1. tricarpellary,
  2. trice,
  3. tricentenary,
  4. tricentennial,
  5. tricep,
  6. triceps reflex,
  7. triceps surae reflex,
  8. triceratops,
  9. trich-,
  10. trichia

Origin of triceps

1570–80; < Latin: three-headed, equivalent to tri- tri- + -ceps, stem -cipit- -headed, derivative of caput head




a triceps muscle, especially the one at the back of the upper arm.

Origin of tricep

First recorded in 1990–95 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for triceps

British Dictionary definitions for triceps


noun plural -cepses (-sɛpsɪz) or -ceps

any muscle having three heads, esp the one (triceps brachii) that extends the forearm

Word Origin for triceps

C16: from Latin, from tri- + caput head

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 triceps



"the great extensor muscle," 1704, from Latin triceps "three-headed," from tri- "three" (see tri-) + -ceps, from caput "head" (see capitulum). So called because the muscle has three origins.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for triceps



n. pl. tri•ceps•es (-sĕp′sĭz)

A three-headed muscle of the upper arm, whose long or scapular head has origin from the lateral border of the scapula, the lateral head, origin from the lateral and posterior surface of the humerus, and the medial head from the posterior surface of the humerus; with insertion into the olecranon of the ulna, with nerve supply from the radial nerve, and whose action extends the forearm; the triceps brachii.
The gastrocnemius and soleus muscles of the calf considered as one muscle; the triceps surae.

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

Science definitions for triceps



The muscle at the back of the upper arm that raises and lowers the forearm. The triceps has three points of attachment to bone at its origin.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.