Definition of: fourth

(fôrth, fōrth) adjective
1. Next in order after the third.
2. Being one of four equal parts.
—noun
1. One of four equal parts of anything; the quotient of a unit divided by four; a quarter.
2. A fourth person, thing, or group.
3. Music a The interval between any note and the fourth note above it in a diatonic scale, counting the starting point as one. b A note at this interval above or below any other, considered in relation to that other; specifically, the fourth above the keynote; the subdominant. c Two notes at this interval written or sounded together; the consonance thus produced. See INTERVAL.
—the Fourth July 4th; Independence Day.
—adverb In the fourth order, rank, or place: also, in formal discourse, fourthly. ♦ Homophone: forth.