"Penguin" is what the French sailors called the Great Auk............. the now extinct,flightless member of the auk family.( guillemot,razorbill,puffin etc)
Though totally unrelated, very simular in apperance and habits to the southern hemispher penguins.
When the sailors first sailed south and discovered large flightless seabirds,they named them penguins due to there simularity to the Great Auk
Taken from the MASSIVE book of Christmas anoraks , 1844 edition
http://en.wikipedia.org/wiki/Great_Auk