The plural octopi is hypercorrect, coming from the mistaken notion that the (term
) in . The plural octopii is based on an incorrect attempt to pluralise the word based on an incorrect assumption of its origin, and is rare and widely considered to be nonstandard.
Sources differ on which plurals are acceptable: (w, Fowler's Modern English Usage)'' asserts that “the only acceptable plural in English is octopuses”, while (Merriam-Webster) and other dictionaries accept (term) as a plural form. The ''(Oxford English Dictionary)
), and (term
) (the order reflecting decreasing frequency of use), stating that the last form is rare.
The term octopod (either plural octopods and octopodes 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 (term
) is usually reserved for animals consumed for food.