Fourth

a.	1.	Next in order after the third; the ordinal of four.
	2.	Forming one of four equal parts into which anything may be divided.
n.	1.	One of four equal parts into which one whole may be divided; the quotient of a unit divided by four.
	2.	(Mus.) The interval of two tones and a semitone, embracing four diatonic degrees of the scale; the subdominant of any key.
	3.	One coming next in order after the third. The Fourth specifically, in the United States, the fourth day of July, the anniversary of the declaration of American independence; as, to celebrate the Fourth.

Noun	1.	fourth - following the third position; number four in a countable series
	2.	fourth - one of four equal parts; "a quarter of a pound" Synonyms: fourth part, one-fourth, quarter, quartern, twenty-five percent
	3.	fourth - the musical interval between one note and another four notes away from it
Adj.	1.	fourth - coming next after the third and just before the fifth in position or time or degree or magnitude; "the quaternary period of geologic time extends from the end of the tertiary period to the present" Synonyms: 4th, quaternary
Adv.	1.	fourth - in the fourth place; "fourthly, you must pay the rent on the first of the month" Synonyms: fourthly

consecutive intervals, degree, diapason, diatessaron, diatonic interval, diatonic semitone, enharmonic diesis, enharmonic interval, farthing, fifth, fourth part, half step, halftone, interval, less semitone, melodic interval, note, octave, one-fourth, parallel octaves, quart, quarter, quartern, quarto, second, semitone, seventh, sixth, step, third, tone, twenty-five cents, twenty-five percent, two bits, unison interval, whole step