• synonyms


[bahy-lat-er-uh l]
  1. pertaining to, involving, or affecting two or both sides, factions, parties, or the like: a bilateral agreement; bilateral sponsorship.
  2. located on opposite sides of an axis; two-sided, especially when of equal size, value, etc.
  3. Biology. pertaining to the right and left sides of a structure, plane, etc.
  4. Chiefly Law. (of a contract) binding the parties to reciprocal obligations.
  5. through both parents equally: bilateral affiliation.Compare unilateral(def 7).
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  1. Informal. a bilateral agreement, especially regarding international trade.
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Origin of bilateral

First recorded in 1765–75; bi-1 + lateral
Related formsbi·lat·er·al·ism, bi·lat·er·al·ness, nounbi·lat·er·al·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for bilaterally

Historical Examples

British Dictionary definitions for bilaterally


  1. having or involving two sides
  2. affecting or undertaken by two parties; mutuala bilateral treaty
  3. denoting or relating to bilateral symmetry
  4. having identical sides or parts on each side of an axis; symmetrical
  5. sociol relating to descent through both maternal and paternal lineageCompare unilateral (def. 5)
  6. British relating to an education that combines academic and technical courses
  7. a bilateral meeting
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Derived Formsbilaterally, adverb
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 bilaterally



"having two sides," 1775, from bi- + lateral. Related: Bilaterally.

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Online Etymology Dictionary, © 2010 Douglas Harper

bilaterally in Medicine


  1. Having or formed of two sides; two-sided.
  2. Having or marked by bilateral symmetry.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.