verb al·ter \ˈl-tər\

: 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


Full Definition of ALTER

transitive verb
:  to make different without changing into something else
:  castrate, spay
intransitive verb
:  to become different
al·ter·abil·i·ty \ˌl-t(ə-)rə-ˈbi-lə-tē\ noun
al·ter·able \ˈl-t(ə-)rə-bəl\ adjective
al·ter·ably \-blē\ adverb
al·ter·er \-tər-ər\ noun

Examples of ALTER

  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.

Origin of ALTER

Middle English, from Medieval Latin alterare, from Latin alter other (of two); akin to Latin alius other — more at else
First Known Use: 14th century

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>.

Rhymes with ALTER

ALTERABILITY Defined for Kids


verb al·ter \ˈl-tər\

Definition of ALTER for Kids

:  to change partly but not completely <… each time he had altered his course. — Walter Farley, The Black Stallion>
Medical Dictionary


transitive verb al·ter \ˈl-tər\
al·teredal·ter·ing \-t(ə-)riŋ\

Medical Definition of ALTER

:  castrate 1, spay


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