Today’s Complicated Octopus Fact comes to us from Answers.com.
“A note on the plural form: Fowler’s Modern English Usage states that ‘the only acceptable plural in English is octopuses’, and that octopi is misconceived and octopodes pedantic. Octopi derives from the mistaken notion that octopus is Latin. It is not. It is (Latinized) Greek, from oktopous, gender masculine, whose plural is oktopodes. If the word were Latin, it would be octopes (‘eight-foot’) and the plural octopedes, analogous to centipedes and millipedes, as the plural form of pes (‘foot’) is pedes. In modern, informal Greek, it is called khtapodi, gender neuter, with plural form khtapodia.”