give testimony in a court of law
"The witness was called to testify about what she saw on the night of the accident."
provide evidence for
"The blood test showed that he was the father"
"Her behavior testified to her incompetence"
To make a declaration, or give evidence, under oath.
"The witness was called to court to testify about what she saw on the night of the incident."
In plain English: To testify means to give your honest opinion about something you saw or heard, usually during an official investigation or court case.
"The witness will testify about what she saw on the night of the accident."
Usage: Use testify specifically in legal contexts where statements are made under oath; avoid using it as a synonym for "say" or "claim" in casual conversation. Do not confuse the verb with its noun form, which refers to the act of giving evidence rather than the witness themselves.
The word testify comes from the Latin phrase testificare, meaning "to make a witness." It entered English through Old French and Middle English, combining the root for witness with a verb meaning to do or make.