octopus

English octopus comes from Latin octōpūs, borrowed from Ancient Greek ὀκτώπους (oktṓpous), a compound of ὀκτώ (oktṓ, "eight") and πούς (poús, "foot").

The word passed from Greek into Latin largely unchanged in form before settling into English, staying true to its original literal meaning throughout.

It's a piecewise doublet of octopod and octopede, both of which also combine the Greek root for "eight" with a word for "foot" or "foot-part."