n. & adj.
--n.
1. the position in a sequence corresponding to that of the number 4 in the sequence 1-4.
2 something occupying this position.
3 the fourth person etc. in a race or competition.
4 each of four equal parts of a thing; a quarter.
5 the fourth (and often highest) in a sequence of gears.
6 Mus. a an interval or chord spanning four consecutive notes in the diatonic scale (e.g. C to F). b a note separated from another by this interval.
--adj. that is the fourth.
Phrases and idioms:
fourth dimension
1. a postulated dimension additional to those determining area and volume.
2 time regarded as equivalent to linear dimensions. fourth estate joc. the press; journalism.
Derivatives:
fourthly adv.
Etymology: OE feortha, feowertha f. Gmc