[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).
  1. Informal. a bilateral agreement, especially regarding international trade.

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. 2018

Examples from the Web for bilaterally

Historical Examples of bilaterally

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
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.

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