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

Agents have also been ordered to place GPS ankle monitors on immigrants who are released unless a federal judge has explicitly told them not to, the supervisor, Nicole Black, testified. — Seth Klamann, Denver Post, 7 Nov. 2026

Fingerprint specialist Gilbert Aguilar, a defense witness, testified that police knew that Simpson's fingerprints did not match the identifiable prints recovered at the crime scene. — Stephanie Nolasco, FOXNews.com, 7 Nov. 2026

After plaintiffs accused Wexner of attempting to evade subpoenas, a federal magistrate judge ultimately ordered him to testify. — Daniel Libit, Sportico.com, 7 Nov. 2026

Elections clerks around California in the week before the election were sent subpoenas to testify before grand juries slated to convene in November. — CBS News, 7 Nov. 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