Fourth (?), a. [OE. fourthe, ferthe, feorthe, AS. feor&edh;a, fr. feower four.]
1.
Next in order after the third; the ordinal of four.
2.
Forming one of four equal parts into which anything may be divided.
© Webster 1913.
Fourth, n.
1.
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.
2. Mus.
The interval of two tones and a semitone, embracing four diatonic degrees of the scale; the subdominant of any key.
The Fourth, specifically, un the United States, the fourth day of July, the anniversary of the declaration of American independence; as, to celebrate the Fourth.
© Webster 1913.