verb al·ter \ ˈȯl-tər \
|Updated on: 15 Aug 2018

Definition of alter

altered; altering play \-t(ə-)riŋ\
1 : to make different without changing into something else
  • an event that altered the course of history
2 : castrate, spay
  • had the puppies altered
: to become different
  • customs that alter with the times


play \ˌȯl-t(ə-)rə-ˈbi-lə-tē\ noun


play \ˈȯl-t(ə-)rə-bəl\ adjective


play \-blē\ adverb


play \-tər-ər\ noun

Examples of alter in a Sentence

  1. Alcohol can alter a person's mood.

  2. He altered his will to leave everything to his sister.

  3. This one small event altered the course of history.

  4. The place has altered in the 10 years since I left.

  5. I'll need to have the dress altered before the wedding.

Recent Examples of alter from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'alter.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of alter

Middle English, from Medieval Latin alterare, from Latin alter other (of two); akin to Latin alius other — more at else

Synonym Discussion of alter

change, alter, vary, modify mean to make or become different. change implies making either an essential difference often amounting to a loss of original identity or a substitution of one thing for another.
    • changed the shirt for a larger size
alter implies a difference in some particular respect without suggesting loss of identity.
    • slightly altered the original design
vary stresses a breaking away from sameness, duplication, or exact repetition.
    • vary your daily routine
modify suggests a difference that limits, restricts, or adapts to a new purpose.
    • modified the building for use by the disabled

ALTER Defined for English Language Learners


Definition of alter for English Language Learners

  • : to change (something)

  • : to make a change to (a piece of clothing) so that it will fit better

  • : to remove the sex organs of (an animal) so that the animal is unable to reproduce

ALTER Defined for Kids


verb al·ter \ ˈȯl-tər \

Definition of alter for Students

altered; altering
: to change partly but not completely
  • … each time he had altered his course.
  • —Walter Farley, The Black Stallion

Medical Dictionary



transitive verb al·ter \ ˈȯl-tər \

medical Definition of alter

altered; altering \-t(ə-)riŋ\
: castrate 1, spay




medical Definition of alter

: one of the distinct identities or personality states manifested in an individual with multiple personality disorder

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subject to rapid or unexpected change

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