Puffinus is a genus of seabirds in the order Procellariiformes. It is made up of about 20 small to medium-sized shearwaters. Two other shearwater genera are named: "Calonectris", which comprises three large shearwaters, and "Procellaria" with another four large species. The latter are usually called 'petrels', although they are thought to be more closely related to the shearwaters than to the other petrels. Even though their name looks like "puffin", the puffins are auks, and not related to the shearwaters in the genus "Puffinus"; the genus name "Puffinus" is actually a New Latin loanword based on the English "puffin".