eight

(meteorology) The proportion of the sky that is obscured by clouds, in eighths (one octa means that one eighth of the sky is obscured, two octas that one quarter is obscured, and so on).

plural of octa

(geometry, also attributively) A polygon with eight sides and eight angles. / (martial arts) Often in the form Octagon: the arena for mixed martial arts.

(music) An interval of twelve semitones spanning eight degrees of the diatonic scale, representing a doubling or halving in pitch frequency. / (music) The pitch an octave higher than a given pitch.

Alternative form of octavate

(obsolete) Consisting of eight; eight in number.

(organic chemistry) Any of the eighteen isomeric aliphatic hydrocarbons (C₈H₁₈) found in petroleum, especially an iso-octane 2,2,4 trimethyl-pentane; they are used as fuels and solvents.

(geometry) Shaped like an octagon, in having eight sides and eight angles.

(paper, printing) A sheet of paper 7 to 10 inches (= 17.78 to 25.4 cm) high and 4.5 to 6 inches (= 11.43 to 15.24 cm) wide, the size varying with the large original sheet used to create it. It is made by folding the original sheet three times to produce eight leaves.