*octav*

n. [ F., fr. L. octava an eighth, fr. octavus eighth, fr. octo eight. See Eight, and cf. Octavo, Utas. ] 1. The eighth day after a church festival, the festival day being included; also, the week following a church festival. “The octaves of Easter.” Jer. Taylor. [ 1913 Webster ]

2. (Mus.) (a) The eighth tone in the scale; the interval between one and eight of the scale, or any interval of equal length; an interval of five tones and two semitones. (b) The whole diatonic scale itself. [ 1913 Webster ]

☞ The ratio of a musical tone to its octave above is 1:2 as regards the number of vibrations producing the tones. [ 1913 Webster ]

3. (Poet.) The first two stanzas of a sonnet, consisting of four verses each; a stanza of eight lines. [ 1913 Webster ]

With mournful melody it continued this octave. Sir P. Sidney. [ 1913 Webster ]

Double octave. (Mus.) See under Double. --
Octave flute (Mus.), a small flute, the tones of which range an octave higher than those of the German or ordinary flute; -- called also piccolo. See Piccolo. [ 1913 Webster ]

4. A small cask of wine, the eighth part of a pipe. [ 1913 Webster ]

a. Consisting of eight; eight. Dryden. [ 1913 Webster ]

n.;pl. Octavos [ L. in octavo; in in + octavo, abl. of octavus. See Octave. ] A book composed of sheets each of which is folded into eight leaves; hence, indicating more or less definitely a size of book so made; -- usually written 8vo or 8°. [ 1913 Webster ]

a. Having eight leaves to a sheet; as, an octavo form, book, leaf, size, etc. [ 1913 Webster ]