To bear witness; make declaration, especially for the purpose of communicating to others a knowledge of some matter not known to them, or for the purpose of establishing some fact.In law, to give testimony, under oath or solemn affirmation, in a cause depending before a court.To serve as evidence; be testimony or proof.To bear witness to; affirm or declare as fact or truth.In law, to state or declare under oath or affirmation, as a witness, before a tribunal.To give evidence of; evince; demonstrate; show.To make known; publish or declare freely.