Dictionary.com
Thesaurus.com
Synonyms

confirm

American  
[kuhn-furm] / kənˈfɜrm /

verb (used with object)

  1. to establish the truth, accuracy, validity, or genuineness of; corroborate; verify.

    This report confirms my suspicions.

    Synonyms:
    validate, authenticate, substantiate, prove
    Antonyms:
    disprove
  2. to acknowledge with definite assurance.

    Did the hotel confirm our room reservation?

  3. to make valid or binding by some formal or legal act; sanction; ratify.

    to confirm a treaty;

    to confirm her appointment to the Supreme Court.

    Antonyms:
    invalidate
  4. to make firm or more firm; add strength to; settle or establish firmly.

    Their support confirmed my determination to run for mayor.

    Synonyms:
    fix
    Antonyms:
    shake
  5. to strengthen (a person) in habit, resolution, opinion, etc..

    The accident confirmed him in his fear of driving.

  6. to administer the religious rite of confirmation to.


confirm British  
/ kənˈfɜːm /

verb

  1. (may take a clause as object) to prove to be true or valid; corroborate; verify

  2. (may take a clause as object) to assert for a second or further time, so as to make more definite

    he confirmed that he would appear in court

  3. to strengthen or make more firm

    his story confirmed my doubts

  4. to make valid by a formal act or agreement; ratify

  5. to administer the rite of confirmation to

"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

Other Word Forms

  • confirmability noun
  • confirmable adjective
  • confirmatory adjective
  • confirmer noun
  • confirmingly adverb
  • nonconfirming adjective
  • preconfirm verb (used with object)
  • reconfirm verb (used with object)
  • unconfirm verb (used with object)
  • unconfirmability noun

Etymology

Origin of confirm

First recorded in 1250–1300; from Latin confirmāre “to strengthen, confirm” ( see con-, firm 1); replacing Middle English confermen, from Old French, from Latin, as above

Explanation

When you need to make sure before you leave that you have a reservation, you often call ahead to confirm, that is, to make sure that your tickets or space are set aside for you. The firm in confirm should give you a clue as to the word's meaning: to shore up or verify something. When you make sure something is set, or firm, you confirm it. The word comes from the Latin con- "together, altogether," and firmāre "make firm," so confirm originally meant roughly "to make (something) altogether firm."

Keep Reading on Vocabulary.com

Vocabulary lists containing confirm

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

On her third visit, as Crain’s condition deteriorated, a doctor did not send Crain to the intensive care unit until he could confirm fetal demise with two ultrasounds.

From Salon • Apr. 20, 2026

She was also provided a bogus but "realistic sounding" crime reference number, and told to confirm her address for the courier.

From BBC • Apr. 18, 2026

Data from the American Association of Individual Investors seems to confirm that view, with the latest reading from April 15 showing 68.3% of respondents remaining “neutral or bearish” on stocks over the next six months.

From Barron's • Apr. 17, 2026

Unesco relied on satellite imagery and local media footage to confirm the palace was damaged.

From The Wall Street Journal • Apr. 17, 2026

Maria had hoped to remain in Surinam long enough to confirm all her discoveries, to repeat them and check her data as she had always done in Europe.

From "The Girl Who Drew Butterflies: How Maria Merian's Art Changed Science" by Joyce Sidman