noun A person who sees an event, typically a crime or accident, take place. (police are appealing for witnesses to the accident) Evidence; proof. (the memorial service was witness to the wide circle of his interest) A member of the Jehovah's Witnesses.
verb See (an event, typically a crime or accident) take place. (a bartender who witnessed the murder) Have knowledge of (an event or change) from personal observation or experience. (what we are witnessing is the birth of a new political entity) (of a person) openly profess one's religious faith. (our duty is to witness to God)