What is the correct plural of octopus?

Question

What is the correct plural of octopus?

Answer 1

I would go with Octopuses.

That is part of the Wikipedia "Plural form of words ending in -us" article:

Currently:

• octopuses is the most common form in the UK as well as the US;
• octopodes is rare,
• and octopi is often objectionable.

The Oxford English Dictionary lists octopuses, octopi and octopodes (in that order);
it labels octopodes "rare", and notes that octopi derives from the mistaken assumption that octōpūs is a second declension Latin noun, which it is not. Rather, it is (Latinized) Ancient Greek, from oktṓpous (ὀκτώπους), gender masculine, whose plural is oktṓpodes (ὀκτώποδες).
If the word were native to Latin, it would be octōpēs ('eight-foot') and the plural octōpedes, analogous to centipedes and mīllipedes, as the plural form of pēs ('foot') is pedes.
In modern Greek, it is called khtapódi (χταπόδι), gender neuter, with plural form khtapódia (χταπόδια).

Answer 2

Octopuses and octopodes are both correct; the former is appropriate modern English, the latter is most appropriate if you're intentionally trying to come off as a pedantic classicist. (I use it regularly.)

Octopoids is the plural of octopoid, not octopus.

Octopi is a mistaken formation based on interpreting octopus as being constructed using a Latin -us suffix when it is in fact constructed using a Greek -pus suffix. (I guarantee you that somebody will write an answer that asserts that it has attained correctness through usage. I contrariwise assert that if ten billion people all jump off a cliff, they're still all stupid.)

(Note: this answer was written for a slightly different question that was merged with the current question, which is why it may seem I was answering oddly.)

Answer 3

Let's find out from the Merriam-Webster's editor:

http://www.youtube.com/watch?v=wFyY2mK8pxk

Answer 4

The NOAD has the following note about the plural of octopus:

USAGE The standard English plural of octopus is octopuses. However, the word octopus comes from Greek, and the Greek plural form is octopodes. Modern usage of octopodes is so infrequent that many people mistakenly create the erroneous plural form octopi, formed according to rules for Latin plurals.

Answer 5

Plural forms of Octopus is: octopuses /ˈɒktəpʊsɪz/, octopi /ˈɒktəpaɪ/, or octopodes /ɒkˈtɒpədiːz/ . See Terminology of Octopus from Wikipedia.

Answer 6

Octopi is based on an incorrect assumption, that octopus is of Latin derivation, so we shouldn't use it. Octopuses sounds funny, so I wouldn't use it. Octopodes may be rare, but it's right, so perhaps it's up to us to get people used to it.