Definitions for "Primary feathers"
Keywords:  feathers, wing, outermost, flight, nine
There are several types of feathers on the wing, each with their own function. Primary feathers are essential to flight, and are the biggest and the largest ones. They are extremely light, but incredibly stiff. Their shafts (the hard stem that supports the feather) are made up of a material very similar to that which makes up your fingernails - hard, durable, and tough. There are ordinarily ten primary feathers.
The large outermost feathers of the wing. They form part of the flight feathers.
The outermost nine or ten feathers of a bird's wings. Primaries are the major flight feathers.