• synonyms


[trahy-mes-ter, trahy-mes-]
  1. a term or period of three months.
  2. one of the three approximately equal terms into which the year is divided by some colleges, schools, etc.
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Origin of trimester

1815–25; < French trimestre < Latin trimē(n)stris of three months, equivalent to tri- tri- + -mē(n)stris (see semester)
Related formstri·mes·tral [trahy-mes-truh l] /traɪˈmɛs trəl/, tri·mes·tri·al, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for trimester

Contemporary Examples

British Dictionary definitions for trimester


  1. a period of three months
  2. (in some US and Canadian universities or schools) any of the three academic sessions
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Derived Formstrimestral or trimestrial, adjective

Word Origin

C19: from French trimestre, from Latin trimēstris of three months, from tri- + mēnsis month
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 trimester


1821, "period of three months," from French trimestre (early 17c.), from Latin trimestris "of three months," from tri- "three" (see tri-) + mensis "month" (see moon (n.)). Specific obstetrics sense is attested from 1916.

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Online Etymology Dictionary, © 2010 Douglas Harper

trimester in Medicine


(trī-mĕstər, trīmĕs′-)
  1. A period of three months.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.