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

Grant and two other members of Banks’s entourage made plea deals and testified against the rapper during the trial. — Bethy Squires, Vulture, 12 Sep. 2026

Kash Patel is back before Congress The FBI director will testify before the Senate Judiciary Committee on Tuesday, the committee announced last week. — Mallorie Sullivan, USA Today, 11 Sep. 2026

But instead of a fun time checking out a new city, her trip turned into a nightmare, Tina testified in a federal courtroom yesterday. — Chicago Tribune, 11 Sep. 2026

Party Chairman Evan Power did not respond to questions about whether the grand jury subpoenaed or seized any party documents or communications as part of its investigation, or invited party officials to testify. — Claire Heddles, Miami Herald, 11 Sep. 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