[fourth] n, pl fourths (bef. 12c) 1: one that is number four in a countable series
2. a: a musical interval embracing four tones of the diatonic scale b: a tone at this interval; specif: subdominant 1 c: the harmonic combination of two tones a fourth apart
3: the 4th forward gear or speed of a motor vehicle
4. cap: independence day--used with the -- fourth adj or adv -- fourth.ly adv