Fugue (Latin fuga, flight), a musical composition, in which a subject, introduced by one part, is copied successively by the other parts in accordance with certain rules. After its introduction by the first part, the subject is repeated by the second part either in the fourth or fifth, while the first part is so arranged as to agree with it, both parts being so regulated that the first cadence may be on the fifth of the key. The subject is then resumed in the same part as at the commencement, but by a different interval, and after a rest of a whole or half a bar, or even longer. The second part is brought in before the first part is concluded, the second cadence being in the third of the key. Finally the subject, being introduced by either part, is taken up sooner than at first by the other part, and the parts are then united and brought to a close by a final cadence. There are various forms of fugue - such as fuga doppia, "double fugue," in which two subjects begin at once in different parts; fuga homophona, in which the answer and imitation of the subject are in unison; fuga irregularis, "free fugue," in which the subject is not treated according to the strict laws of fugue-writing, etc. Vocal fugues are subject to the same rules as those written for instruments. Sebastian Bach holds the most distinguished place amongst fugue-writers. These include all the eminent composers of both old and modern times, but none of them has approached him in this branch of music.