Origin of octa-Classical Greek okta- from okt?, eight
Octa is defined as eight.
An octopus, with eight legs, is an example of octa.
- (meteorology) The fraction 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).
- When heated to about 200° it yields a brown amorphous substance, named caramel, used in colouring liquors, &c. Concentrated sulphuric acid gives a black carbonaceous mass; boiling nitric acid oxidizes it to d-saccharic, tartaric and oxalic acids; and when heated to 160° with acetic anhydride an octa-acetyl ester is produced.
- It is oxidized by nitric acid to d-saccharic and mucic acids; and acetic anhydride gives an octa-acetate.