means A flightless seabird of the Southern Hemisphere with black-and-white plumage and flipper-like wings, built for swimming rather than flying.

from The name is genuinely murky. The favorite theory traces it to Welsh 'pen gwyn,' meaning 'white head' — but the catch is that the bird originally called 'penguin' was the great auk of the North Atlantic, a now-extinct flightless seabird that sailors lumped together with these southern lookalikes. Some doubt the Welsh story (the auk's head was mostly black) and propose Latin 'pinguis,' 'fat,' for its plump build. The honest answer: the word was applied to the auk first, the southern birds inherited it by resemblance, and the precise root remains debated.