Definition of Fourth

Fourth

1. Next in order after the third; the ordinal of four.
2. Forming one of four equal parts into which anything may be divided.
3. One of four equal parts into which one whole may be divided; the quotient of a unit divided by four; one coming next in order after the third.
4. The interval of two tones and a semitone, embracing four diatonic degrees of the scale; the subdominant of any key.