BEAT, a blow or stroke; from the many applications of the verb "to beat" come various meanings of the substantive. It is applied to the throbbing of the pulse or heart and to the beating of a drum; in music to the alternating sound produced by the striking together of two notes not exactly of the same pitch (see SOUND), and to the movement of the baton by which a conductor of an orchestra or chorus indicates the time. In navigation a "beat" is one of the courses taken by a ship in sailing against the wind. The word is also applied to a policeman's or sentry's round.