testify

verb

tes·​ti·​fy ˈte-stə-ˌfī 

testified; testifying

intransitive verb

1

: to make a solemn declaration under oath for the purpose of establishing a fact (as in a court)

2

a

: to make a statement based on personal knowledge or belief : bear witness

b

: to serve as evidence or proof

3

: to express a personal conviction

transitive verb

1

a

: to bear witness to : attest

b

: to serve as evidence of : prove

2

: to declare under oath before a tribunal or officially constituted public body

3

archaic

a

: to make known (a personal conviction)

b

: to give evidence of : show

testifier

ˈte-stə-ˌfī(-ə)r 

noun

Synonyms of testify

• swear
• witness
• attest
• verify

Examples of testify in a Sentence

She refused to testify about who had given her the information.

She testified before Congress today.

He agreed to testify against his drug dealer.

He testified that he'd seen two people leave the building on the night of the murder.

These statistics testify that the program is working.

Several people testified during the revival meeting.

Recent Examples on the Web

Link testified over two days about his undercover role, receiving a break at sentencing for his own tax conviction. — Jason Meisner, Chicago Tribune, 28 Aug. 2026

Former Palm Beach County State Attorney Dave Aronberg, a Democrat, said Uthmeier likely wasn’t called to testify because the grand jury didn’t want to offer him immunity. — Grethel Aguila, Miami Herald, 28 Aug. 2026

The case has gripped television and online trial watchers after several witnesses testified that Clancy was a good and devoted mother for years before her mental health deteriorated after giving birth to her third child. — Aysha Bagchi, USA Today, 28 Aug. 2026

In an agreement with the state, Josiah Hoffman, the other person indicted in Snellings’ death, in late July pleaded guilty to murder in exchange for a 35-year prison sentence and commitment to testify truthfully against Greer at trial. — Emerson Clarridge, Fort Worth Star-Telegram, 28 Aug. 2026

Word History

Etymology

Middle English testifien, from Anglo-French testifier, from Latin testificari, from testis witness

First Known Use

14th century, in the meaning defined at intransitive sense 2a

Phrases Containing testify

• testify for the defense/prosecution

Rhymes for testify

• abscissae
• adonai
• alibi
• alkali
• alumni
• amoebae
• amplify
• annuli
• beautify
• brachii
• butterfly
• calculi

Kids Definition

testify

verb

tes·​ti·​fy ˈtes-tə-ˌfī 

testified; testifying

1

a

: to make a statement based on personal knowledge or belief

could testify to the student's devotion to her studies

b

: to make a formal statement of what one swears is true

testified in court

2

: to give outward proof : serve as a sign of

yawns testifying to fatigue

testifier

-ˌfī(-ə)r 

noun

Legal Definition

testify

verb

tes·​ti·​fy ˈtes-tə-ˌfī 

testified; testifying

intransitive verb

: to make a solemn declaration under oath or affirmation for the purpose of establishing a fact : give testimony

transitive verb

: to declare in testimony

testifier noun

Etymology

Latin testificari, from testis witness