[ awl-ter ]
See synonyms for alter on
verb (used with object)
  1. to make different in some particular, as size, style, course, or the like; modify: to alter a coat; to alter a will; to alter course.

  2. to castrate or spay.

verb (used without object)
  1. to change; become different or modified.

Origin of alter

First recorded in 1350–1400; Middle English, from Old French alterer, from Late Latin alterāre “to change, worsen,” derivative of Latin alter “other”

synonym study For alter

1. See adjust,

Other words from alter

  • al·ter·er, noun
  • half-altered, adjective
  • pre·al·ter, verb (used with object)
  • re·al·ter, verb
  • un·al·ter·ing, adjective
  • well-altered, adjective

Words that may be confused with alter

Other definitions for Alter (2 of 3)

[ awl-ter ]

  1. David, 1807–81, U.S. physicist.

Other definitions for alter. (3 of 3)


  1. alteration. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use alter in a sentence

British Dictionary definitions for alter


/ (ˈɔːltə) /

  1. to make or become different in some respect; change

  2. (tr) informal, mainly US a euphemistic word for castrate, spay

Origin of alter

C14: from Old French alterer, from Medieval Latin alterāre to change, from Latin alter other

Derived forms of alter

  • alterable, adjective
  • alterably, adverb
  • alterability, noun

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