The word penguin was a 16th century synonym for which bird?

The penguins are a group of aquatic flightless birds living almost exclusively in the Southern Hemisphere.

The word penguin first appeared in the 16th century as a synonym for the great auk, a bird that is now extinct. When European explorers discovered what are today known as penguins in the Southern Hemisphere, they noticed their similarity in appearance to the great auk of the Northern Hemisphere, and named them after this bird.

The great auk was a species of flightless alcid (alcid, from the family ‘Alcidea’, the scientific name from the Linnaeus classification system that included auks) that became extinct in the mid-19th century. The great auk was not closely related to the birds known as penguins which were discovered later by Europeans so named by sailors because of their physical resemblance to the great auk.

The etymology of the word penguin is still debated. Some dictionaries including the ‘Oxford English Dictionary’ suggest the word penguin is a derivation from the Welsh word ‘pen’ (head) and ‘gwyn’ (white).

An alternative etymology links the word penguin to the Latin ‘pinguis’ (fat or oil). Support for this etymology can be found in the alternative Germanic word for penguin, ‘fettgans’ (fat-goose), and the related Dutch word ‘vegans’

Adult male penguins are called ‘cocks’, while females are ‘hens’ and a group of penguins on land is a ‘waddle’ and a group of penguins in the water is a ‘raft’.