- octopus
- 1758, genus name of a type of eight-armed cephalopod mollusks, from Gk. oktopous "eight-footed," from okto "eight" (see eight) + pous "foot." Proper plural is octopodes, though octopuses probably works better in English. Octopi is from mistaken assumption that -us is the L. noun ending that takes -i in plural.
- polyp
- c.1400, "nasal tumor," from L. polypus "cuttlefish," also "nasal tumor," from Gk. (Doric, Aeolic) polypos "octopus, cuttlefish," from polys "many" (see plenary) + pous "foot." Sense extended 1742 to hydras and sea anemones (earlier polypus, c.1520).