al·​ter | \ˈȯl-tər \
altered; altering\-​t(ə-​)riŋ \

Definition of alter 

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

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Other Words from alter

alterability \ˌȯl-​t(ə-​)rə-​ˈbi-​lə-​tē \ noun
alterable \ˈȯl-​t(ə-​)rə-​bəl \ adjective
alterably \-​blē \ adverb
alterer \-​tər-​ər \ noun

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

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.
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Recent Examples on the Web

Many intermittent fasting proponents claim that IF further triggers fat loss by altering hormone levels, but experts say that these hormone changes aren't significant enough to cause weight loss in this way. SELF, "What You Need to Know Before Trying Intermittent Fasting," 7 Nov. 2018 Other brands and agencies have altered the length of text in a digital message to match how fast the traffic is moving by or the message itself based on the time of day. Rani Molla, Recode, "Billboards — yes, billboards — are having a heyday in a digital world," 25 Sep. 2018 Individuality was the team’s main inspiration for Spring, and their (somewhat repetitive) use of on-trend drawstrings was a way to translate thought into action, allowing wearers to customize and alter the fit of the pieces. Vogue, "Designers Opt for Opulence Over Minimalism on the Second Day of Oslo Runway," 16 Aug. 2018 Using multiple digital tools, Mr. Kadar was able to mask his identity, alter his voice, hide his phone number and reroute his internet traffic through intermediaries, according to the charging documents. Niraj Chokshi, New York Times, "Israeli Judge Convicts Man on Charges of Threatening U.S. Jewish Groups," 28 June 2018 Mexico’s next president may inherit stalled negotiations on NAFTA, which the Trump administration is trying to alter to be more favorable to American workers. Kevin Sieff, Washington Post, "The story must be told.," 20 June 2018 The idea, usually, is to alter organisms in the gut, where about 99 percent of human microbiota live. Fortune, "Why Washing Your Hands Too Much Could Make You Sick," 12 June 2018 The implications of the U.S.’s new Countering America’s Adversaries Through Sanctions Act (CAATSA), whose primary aim is to alter Russia’s international behaviour, would be far-reaching on India. Vinay Kaura, Time, "Strategic Ties Between India and the U.S. Are Growing. But Russia Is a Stumbling Block," 11 June 2018 By bringing guaranteed shipping over to crowdfunding, Indiegogo is fundamentally altering the practice of backers risking their money to support a creator. Ashley Carman, The Verge, "Indiegogo will withhold certain crowdfunding campaigns’ funds until they ship," 14 Nov. 2018

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.

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First Known Use of alter

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

History and Etymology for alter

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

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Statistics for alter

Last Updated

5 Dec 2018

Look-up Popularity

Time Traveler for alter

The first known use of alter was in the 14th century

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More Definitions for alter



English Language Learners Definition of alter

: 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


al·​ter | \ˈȯl-tər \
altered; altering

Kids Definition of alter

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

al·​ter | \ˈȯl-tər\
altered; altering\-​t(ə-​)riŋ \

Medical Definition of alter 

(Entry 1 of 2)



Medical Definition of alter (Entry 2 of 2)

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

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More from Merriam-Webster on alter

Rhyming Dictionary: Words that rhyme with alter

Thesaurus: All synonyms and antonyms for alter

Spanish Central: Translation of alter

Nglish: Translation of alter for Spanish Speakers

Britannica English: Translation of alter for Arabic Speakers

Comments on alter

What made you want to look up alter? Please tell us where you read or heard it (including the quote, if possible).


a nest or breeding place

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