1. In law, to question a witness or suspect after the opposing side has already done so, as to undermine or clarify their testimony. I have doubts that that witness is telling the truth, and I'll expose it when I cross-examine him.
2. By extension, to question someone thoroughly. Geez Mom, why are you cross-examining me? I told you the truth—I was at Kelly's house all night.
to question someone in court who has already been questioned by the opposing side; to question a suspect or a witness at great length. The lawyer plans to cross-examine the witness tomorrow morning. The police cross-examined the suspect for three hours.