pigeonhole

Concise Oxford English Dictionary © 2008 Oxford University Press:
pigeonhole/ˈpɪʤɪnhəʊl/

▶noun

• 1 a small recess for a domestic pigeon to nest in.

• 2 each of a set of small compartments where letters or messages may be left for individuals.

• 3 a category, especially an overly restrictive one, to which someone or something is assigned.

▶verb

• 1 assign to a particular category, especially an overly restrictive one.

• 2 deposit (a document) in a pigeonhole.