Secondary (feather)
One of the inner flight feathers ('remiges') of a bird's wing, between the primary and tertiary feathers. The secondaries vary in number from nine to twenty, according to the type of bird, and they are embedded in the skin of the bird's 'forearm'. Their chief use is in propulsion.From Peter Weaver's Birdwatcher's Dictionary
Copyright © 1981 by Peter Weaver