Etymology

From from + .

Noun

(see usage note regarding plurals)

1. Any of several marine molluscs/mollusks, of the family Octopodidae, having no internal or external protective shell or bone (unlike the nautilus, squid or cuttlefish) and eight arms each covered with suckers.
2. The flesh of these marine molluscs eaten as food.
3. An organization that has many powerful branches controlled from the centre.

Usage notes

The plural is hypercorrect, coming from the mistaken notion that the in is a Latin second declension ending. The word is actually treated as a third declension noun in Latin. The plural follows the Ancient Greek plural, .

Sources differ on which plurals are acceptable: Fowler’s Modern English Usage asserts that “the only acceptable plural in English is ”, while Merriam-Webster and other dictionaries accept as a plural form. The Oxford English Dictionary lists , , and (the order reflecting decreasing frequency of use), stating that the last form is rare.

The term (either plural and can be found) is taken from the taxonomic order Octopoda but has no classical equivalent, and is not necessarily synonymous (it can encompass any member of that order). The collective form is usually reserved for animals consumed for food.