Late 16th century (originally denoting the great auk): possibly of Welsh origin, from pen gwyn 'white head'.

• Penguin is a rare example of a word that is probably from Welsh, in this case from pen gwyn ‘white head’. It is even rarer for a Welsh word to become internationally adopted for the name of a thing. Sailors and fishermen first gave the name penguin to the great auk of the seas around Newfoundland, which the penguin resembled closely, both birds being large, flightless waterfowl with black and white plumage adapted to life in freezing waters. British sailors may have mistaken penguins for great auks, or simply applied a term they knew to a previously unseen bird. Penguins have fared rather better than great auks: penguins are popular and much studied, whereas great auks were hunted to extinction, the last killed on an islet off Iceland in 1844.