pennŭla — Lewis & Short
pennŭla, ae, f.dim.id.,
I a little wing (rare but class.):
cum pulli pennulis uti possunt,Cic. N. D. 2, 52, 129: tensa, Ven. Carm. 3, 22, 9; Hieron. adv. Pelag. 1, 14 init.; Vulg. Lev. 5, 8.