Where does the name Penguin come from? Nobody is really sure, but there are three main suggestions. One is based on the Welsh or Breton Gaelic name for another bird, now extinct, the Great Auk, called pen (head) gwyn (white) because of white patches in front of its eyes. The Great Auk lived in the North Atlantic area, and the connection to the Antarctic, where penguins live, could be the sailors from Newfoundland, who called the Great Auk "pin-wing", because its wings were short and thin.

They thought penguins looked very similar, so maybe the name got transferred to them. The third possibility is based on the Latin word pinguis, meaning "fat", because medieval maps of the world were labeled in Latin, including unusual creatures that sailors found in faraway places. All of these names date back before the year 1600, so there's no conclusive evidence - but it's interesting that the Slovak name is "tučniak" after all.