[ bahy-lat-er-uh l ]
/ baɪˈlæt ər əl /


pertaining to, involving, or affecting two or both sides, factions, parties, or the like: a bilateral agreement; bilateral sponsorship.
located on opposite sides of an axis; two-sided, especially when of equal size, value, etc.
Biology. pertaining to the right and left sides of a structure, plane, etc.
Chiefly Law. (of a contract) binding the parties to reciprocal obligations.
through both parents equally: bilateral affiliation.Compare unilateral(def 7).


Informal. a bilateral agreement, especially regarding international trade.

Nearby words

  1. bikol,
  2. bikram yoga,
  3. bilabial,
  4. bilabiate,
  5. bilander,
  6. bilateral hermaphroditism,
  7. bilateral symmetry,
  8. bilateral trade,
  9. bilateralism,
  10. bilayer

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

Examples from the Web for bilateral

British Dictionary definitions for bilateral


/ (baɪˈlætərəl) /


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 bilateral



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

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for bilateral


[ bī-lătər-əl ]


Having or formed of two sides; two-sided.
Having or marked by bilateral symmetry.

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