Any of several species of umbrella octopuses of the genus Grimpoteuthis.

Any of four species of pelagic octopus of the genus Tremoctopus, found in tropical and subtropical oceans.

(chemistry) Any compound containing eight carbonate groups in each molecule or unit cell

An Indo-Pacific species of octopus, Thaumoctopus mimicus, capable of impersonating other species of marine life.

(organic chemistry) Any compound that has eight acetate groups (typically of a sugar)

The Australian octopus Octopus tetricus

(inorganic chemistry, in combination) Eight calcium atoms or ions in a compound

Any octopus of the genus Hapalochlaena, with distinctive blue rings, that carry the highly poisonous venom tetrodotoxin (TTX).

Alternative form of octatomic

(of fuel) Having a low octane number. / (by extension) Slow; weak.