testify

American  

[tes-tuh-fahy] / ˈtɛs təˌfaɪ /

verb (used without object)

testified, testifying

1. to bear witness; give or afford evidence.

2. Law. to give testimony under oath or solemn affirmation, usually in court.

3. to make solemn declaration.

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verb (used with object)

testified, testifying

1. to bear witness to; affirm as fact or truth; attest.

2. to give or afford evidence of in any manner.

   Synonyms:

   prove, signify, show, indicate

3. Law. to state or declare under oath or affirmation, usually in court.

4. to declare, profess, or acknowledge openly.

testify British  

/ ˈtɛstɪˌfaɪ /

verb

1. (when tr, may take a clause as object) to state (something) formally as a declaration of fact

   I testify that I know nothing about him

2. law to declare or give (evidence) under oath, esp in court

3. to be evidence (of); serve as witness (to)

   the money testified to his good faith

4. (tr) to declare or acknowledge openly

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Other Word Forms

• pretestify verb (used with object)
• retestify verb
• testification noun
• testifier noun
• untestifying adjective

Etymology

Origin of testify

1350–1400; Middle English testifyen < Latin testificārī to bear witness, equivalent to testi ( s ) witness + -ficārī -fy

Explanation

To testify is to make a statement or provide evidence, usually in court. Witnesses testify for the prosecution or defense. If you've ever seen a TV show about lawyers, you've probably seen someone testifying: putting their hand on the Bible, sitting in the witness seat, and telling what they know about a case. Testifying is serious business, but it doesn't always happen in court: If someone knows you're good at math, they can testify to your math skills. Or if you've been to a restaurant, you can testify to your friends that it has awesome desserts.

Example Sentences

Woods’s courtroom success was itself notable: African-Americans had only recently secured the constitutional right to testify in federal courts.

From The Wall Street Journal • Apr. 18, 2026

As he and others testify, he hated to lose and to a degree that mitigated the joy of winning.

From The Wall Street Journal • Apr. 14, 2026

"She must come in to testify immediately, and if she defies the subpoena, we will begin contempt charges," he wrote in a statement.

From BBC • Apr. 8, 2026

More than 75 witnesses and about 20 experts are to testify during the proceedings, which are due to run through April.

From Barron's • Apr. 7, 2026

White stationed extra guards at the jail after attempts to break out the outlaws who were going to testify against Hale.

From "Killers of the Flower Moon" by David Grann

Related Words

• announce
• argue
• assert
• declare
• depose
• indicate
• swear