; class Aves)
An order of birds all of which have a short, thick humerus, a short ulna, and short secondary feathers. They are high-speed fliers. The order comprises three families. Trochilidae (humming-birds) are placed in a different suborder from Apodidae (swifts) and Hemiprocnidae (tree swifts).
Subjects: Zoology and Animal Sciences.