Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
octopus (n.)
has two plurals: octopuses (pronounced AHK-tuh-pus-iz) and octopi (pronounced AHK-tuh-pei). Octopod is a relatively rare word, referring to any eight-footed mollusk, including the octopus; octopod has two plurals: octopods (pronounced AHK-tuh-podz) and octopodes (pronounced ahk-TAH-puh-deez). See FOREIGN PLURALS.
