nounplural noun octopuses
A cephalopod mollusc with eight sucker-bearing arms, a soft body, strong beaklike jaws, and no internal shell.
Order Octopoda, class Cephalopoda: Octopus and other genera
The standard plural in English of octopus is octopuses. However, the word octopus comes from Greek, and the Greek plural form octopodes is still occasionally used. The plural form octopi is mistakenly formed according to rules for Latin plurals, and is therefore incorrect
Mid 18th century modern Latin, from Greek oktōpous (see Octopoda).