testify

1 of 2

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

testifier

2 of 2

noun

tes·​ti·​fi·​er ˈtestəˌfī(ə)r 

-īə

plural -s

: one that testifies : witness

especially : a religious proselyte

Synonyms of testify

Verb

• swear
• witness
• attest
• verify

Examples of testify in a Sentence

Verb

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

Verb

One wounded witness was jailed after failing to appear in court, while another initially invoked his Fifth Amendment right against self-incrimination before a judge granted him immunity and ordered him to testify. — Daniel Hunt, Sacbee.com, 3 Oct. 2026

Rubin testified before Congress on behalf of the Unified Government and other fire departments in 2025, opposing fire truck manufacturer monopolies. — Kendrick Calfee, Kansas City Star, 3 Oct. 2026

The probe, which comes one day after top tech leaders signed a self-regulatory AI accord at the White House, could compel tech CEOs to testify before Congress. — Nicholas Wu, semafor.com, 2 Oct. 2026

The third defendant, then-18-year-old Shadolla Peterson, who acted as a lookout while her two friends carried out the attack, testified for the state and avoided the death penalty. — Landon Mion, FOXNews.com, 2 Oct. 2026

Word History

Etymology

Verb

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

First Known Use

Verb

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

Verb

Latin testificari, from testis witness