What is Pigeonhole?

Pigeonhole definition and meaning on Dictionary terms:
one of a series of small, open compartments, as in a desk, cabinet, or the like, used for filing or sorting papers, letters, etc.
a hole or recess, or one of a series of recesses, for pigeons to nest in.

Also called pigeon hole, white hole. Printing. white space created by setting words or lines too far apart.

verb (used with object), pi