• synonyms


[trahy-noh-mee-uh l]
  1. Algebra. consisting of or pertaining to three terms.
  2. Biology.
    1. pertaining to a scientific name comprising three terms, as of genus, species, and subspecies or variety.
    2. characterized by the use of such names.
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  1. Algebra. an expression that is a sum or difference of three terms, as 3x + 2y + z or 3x3 + 2x2 + x.
  2. Biology. a trinomial name, as Rosa gallica pumila.
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Origin of trinomial

First recorded in 1665–75; tri- + (bi)nomial
Related formstri·no·mi·al·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for trinomial

Historical Examples

  • A trinomial in algebra is a quantity consisting of three terms.


    Elmer W. Cavins

  • I have sometimes loosely speculated on what nomenclature would come to, and concluded that it would be trinomial.

  • Duellman used the trinomial for this population and named a new subspecies, pallidus, from Nayarit.

  • The trinomial is used whenever subspecific identities could be made with a reasonable degree of certainty.

British Dictionary definitions for trinomial


  1. maths consisting of or relating to three terms
  2. biology denoting or relating to the three-part name of an organism that incorporates its genus, species, and subspecies
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  1. maths a polynomial consisting of three terms, such as ax ² + bx + c
  2. biology the third word in the trinomial name of an organism, which distinguishes between subspecies
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Derived Formstrinomially, adverb

Word Origin

C18: tri- + -nomial on the model of binomial
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 trinomial

1670s, from tri- + second element from binomial.

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Online Etymology Dictionary, © 2010 Douglas Harper

trinomial in Science


  1. A mathematical expression that is the sum of three monomials, such as ax2 + bx - c.
  2. A taxonomic designation indicating genus, species, and subspecies or variety, as in Brassica oleracea botrytis, the cauliflower.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.