alter

1 of 2

verb

al·​ter ˈȯl-tər 

altered; altering ˈȯl-t(ə-)riŋ 

transitive verb

1

: to make different without changing into something else

an event that altered the course of history

2

: castrate, spay

had the puppies altered

intransitive verb

: to become different

customs that alter with the times

alterability

ˌȯl-t(ə-)rə-ˈbi-lə-tē 

noun

alterable

ˈȯl-t(ə-)rə-bəl 

adjective

alterably

ˈȯl-t(ə-)rə-blē 

adverb

alterer

ˈȯl-tər-ər 

noun

alterable

2 of 2

adjective

al·​ter·​able ˈȯl-t(ə-)rə-bəl 

: capable of being altered

alterably

ˈȯl-t(ə-)rə-blē 

adverb

Synonyms of alter

Verb

• modify
• change
• remodel

Choose the Right Synonym for 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

Examples of alter in a Sentence

Verb

Alcohol can alter a person's mood.

He altered his will to leave everything to his sister.

This one small event altered the course of history.

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

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

Recent Examples on the Web

Verb

Based on the bestselling novel by Bart Baker, Honeymoon with Harry follows a rough-around-the-edges man (Gyllenhaal) who ends up sharing an unwanted journey with his fiancée’s prickly, overprotective father (Costner) after a life-altering turn upends their plans. —Matt Grobar, Deadline, 8 June 2026

Miami real estate developer George Pino is standing trial in a case stemming from a 2022 boat crash in Biscayne Bay that killed one of his daughter's teen friends and left another passenger with life-altering injuries. —Cbs Miami Team, CBS News, 8 June 2026

In the Gables, Parking Director Monica Beltran and her team of parking enforcers are on the watch for fake and altered disability permits. —Michelle Marchante, Miami Herald, 8 June 2026

What the Virginia Tech Epigenetics Study Found The March 2026 review in Cells, led by Sumita Mishra at the Fralin Biomedical Research Institute, examined how estrogen loss alters the epigenome, the system of biological switches that controls which genes turn on and off inside cells. —Allison Palmer, Fort Worth Star-Telegram, 8 June 2026

Word History

Etymology

Verb

Middle English alteren "to change, transform," borrowed from Anglo-French & Late Latin; Anglo-French alterer, borrowed from Late Latin alterāre, verbal derivative of Latin alter "second, another, next," derivative, with the suffix of opposition -ter-, from the base of alius "other" — more at else entry 1

First Known Use

Verb

14th century, in the meaning defined at transitive sense 1

Adjective

1574, in the meaning defined above

Phrases Containing alter

• alter ego

Rhymes for alter

• altar
• falter
• halter
• psalter
• salter
• defaulter

Kids Definition

alter

verb

al·​ter ˈȯl-tər 

1

: to change partly but usually not completely

alter a dress

2

: castrate, spay

alterability

ˌȯl-t(ə-)rə-ˈbil-ə-tē 

noun

alterable

ˈȯl-t(ə-)rə-bəl 

adjective

alterer noun

Etymology

Verb

Middle English alteren "to make different," from Latin alterare (same meaning), from Latin alter "other (of two)" — related to adulterate

Medical Definition

alter

1 of 2 transitive verb

al·​ter

ˈȯl-tər

altered; altering

-t(ə-)riŋ

: castrate sense 1, spay

alter

2 of 2 noun

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