verb (used with object)

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.
to castrate or spay.

verb (used without object)

to change; become different or modified.

Origin of alter

1350–1400; Middle English < Old French alterer < Late Latin alterāre to change, worsen, derivative of Latin alter other
Related formsal·ter·er, nounhalf-al·tered, adjectivepre·al·ter, verb (used with object)re·al·ter, verbun·al·ter·ing, adjectivewell-al·tered, adjective
Can be confusedaltar alter

Synonym study

1. See adjust, change. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for unaltering

Historical Examples of unaltering

  • In all but the unaltering fire of friendship I could see change creeping on.

  • Let your altar be to the 'Unknown God,' if you like—for who can give an unaltering likeness to the Power above us?


    H. Rider Haggard

  • It was practised for thousands of years and opposed its unaltering form to the multiplicity of legends and local beliefs.

  • Her face wore a settled and unaltering expression of something missed yet never to that day for one moment forgotten.

  • The tree waves softly all night in the unaltering lamplight, and the moonlight is killed upon its leaves.

    London Impressions

    Alice Meynell

British Dictionary definitions for unaltering



to make or become different in some respect; change
(tr) informal, mainly US a euphemistic word for castrate, spay
Derived Formsalterable, adjectivealterably, adverbalterability, noun

Word Origin for alter

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



late 14c., "to change (something)," from Old French alterer "change, alter," from Medieval Latin alterare "to change," from Latin alter "the other (of the two)," from PIE *al- "beyond" (see alias (adv.)) + comparative suffix -ter (cf. other). Intransitive sense "to become otherwise" first recorded 1580s. Related: Altered; altering.

Online Etymology Dictionary, © 2010 Douglas Harper