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testify against (someone or something)
To present evidence or testimony against someone or something as a witness in a trial. I refused to testify against the mob boss unless the police were able to guarantee the safety of my family. Spouses cannot be made to testify against one another.
testify for (someone or something)
To present evidence or testimony in favor or defense of someone or something as a witness in a trial. The doctor was asked to testify for the plaintiff in the criminal negligence lawsuit against the construction company. I agreed to testify for Daniel, since I was with him the night of the incident.
testify to (something)
To give sworn testimony that something is true. The doctor was asked to testify to the extent of the plaintiff's injuries in the criminal negligence lawsuit against the construction company. I was happy to testify for Daniel's whereabouts on the evening in question, as I had been with him the whole night.
testify against someone or something
to be a witness against someone or something. Who will testify against him in court? I cannot testify against the company I work for.
testify for someone
to present evidence in favor of someone; to testify on someone's behalf. I agreed to testify for her at the trial. Max testified for Lefty, but they were both convicted.
testify to something
to swear to something. I will testify to your whereabouts if you wish. I think I know what happened, but I would not testify to it.
1. To make a statement based on personal knowledge in support of some asserted fact; bear witness to something: Many astronauts have testified to the thrill of weightlessness. The witness testified to the accuracy of the defendant's story.
2. To serve as evidence: The wreckage testifies to the strength of the storm.