• (n. pl.) An order of birds, including only the penguins, in which the wings are without quills, and not suited for flight.
Im·pen'nes noun plural [ New Latin , from Latin prefix im- not + penna feather.] (Zoology) An order of birds, including only the penguins, in which the wings are without quills, and not suited for flight. 
Impennes is a name given to swimming birds which have only rudimentary feathers, such as penguins.