This word is not the opposite of antagonist (one who contends with another); the pair must not be used as synonyms of supporter and opponent, the pros and the antis. Protagonist has nothing to do with the Latin word pro: its beginning is derived from a Greek word meaning first, and it means literally the principal actor in a play; hence it is used for the most prominent personage in any affair. It is not necessarily associated with the advocacy of anything, although it often happens to be so in fact. When we say that Mr. Willett was protagonist in the movement for summer time, we are not saying that he was pro summer time; we are saying that he played a leading part in the movement. Protagonist should never be used in the sense merely of advocate or champion.