[ awl-ter ]
/ ˈɔl tər /

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.

Nearby words

  1. altazimuth mounting,
  2. altdorf,
  3. altdorfer,
  4. altdorfer, albrecht,
  5. alte pinakothek,
  6. alter ego,
  7. alter idem,
  8. alter.,
  9. alterable,
  10. alterant

Origin of alter

1350–1400; Middle English < Old French alterer < Late Latin alterāre to change, worsen, derivative of Latin alter other

Related forms
Can be confusedaltar alter

Synonym study

1. See adjust, change.


[ awl-ter ]
/ ˈɔl tər /


David,1807–81, U.S. physicist.


[ alt ]
/ ælt /



in alt, in the first octave above the treble staff.

Origin of alt

1525–35; < Provençal < Latin altum, noun use of neuter of altus high


alter idem

[ ahl-ter ee-dem; English awl-ter ahy-dem, al- ]
/ ˈɑl tɛr ˈi dɛm; English ˈɔl tər ˈaɪ dɛm, ˈæl- /

noun Latin.

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

Examples from the Web for alter

British Dictionary definitions for alter


/ (ˈɔːltə) /


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


/ (ælt) music /


(esp of vocal music) high in pitch
of or relating to the octave commencing with the G above the top line of the treble staff


in alt in the octave directly above the treble staff

Word Origin for alt

C16: from Provençal, from Latin altus high, deep

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 alter



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

Medicine definitions for alter


[ ā′ĕl-tē ]


alanine aminotransferase

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