(noun) A small recess (usu. one of a series) for a domestic pigeon to nest in; transf. a small room, apartment, etc. Formerly also (Criminals' slang) the stocks; an instrument in which the hands of culprits were confined, when being flogged
(noun) a.) Any of a series of compartments in a desk or on a wall, open in front, for keeping and sorting papers, letters, etc. b.) fig. Any of a series of categories for the classification of facts, ideas, people, etc. "R. H. Morrieson - I had privately consigned Len Ramsbottom to the pigeon-hole 'lousiest typist ever'."
Assign to a definite place in the memory, or in an ordered group of ideas; categorize mentally. "National Times - He was labelled schizophrenic, a diagnosis flung around to pigeon-hole misfits