pigeonhole

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A small compartment or recess, as in a desk, for holding papers; a cubbyhole.
• noun A specific, often oversimplified category.
• noun The small hole or holes in a pigeon loft for nesting.
• transitive verb To place or file in a small compartment or recess.
• transitive verb To classify mentally; categorize.
• transitive verb To put aside and ignore; shelve.

from The Century Dictionary.

• To place or file away in a pigeonhole; hence, to lay aside for future consideration; hence, to lay aside and ignore or forget; “shelve”; treat with intentional neglect: as, to pigeonhole an application for an appointment; to pigeonhole a scheme.
• noun One of the holes in a dove-cote or pigeon-house through which the birds pass in and out.
• noun Hence A little compartment or division in a case for papers, a bureau, a desk, or the like.
• noun One of a series of holes in an arch of a furnace through which the gases of combustion pass.
• noun One of a series of holes in the block at the bottom of a keir through which its liquid contents can be discharged.
• noun plural An old English game, resembling modern bagatelle, in which balls were rolled through little cavities or arches.
• noun In printing, an over-wide space between printed words. Also called rat-hole.

from the GNU version of the Collaborative International Dictionary of English.

• noun A small compartment in a desk or case for the keeping of letters, documents, etc.; -- so called from the resemblance of a row of them to the compartments in a dovecote.
• transitive verb To place in the pigeonhole of a case or cabinet; hence, to put away; to lay aside indefinitely.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A nook in a desk for holding papers.
• noun One of an array of compartments for sorting post, messages etc. at an office, or college (for example).
• noun A hole, or roosting place for pigeons.
• verb To categorize; especially to limit or be limited to a particular category, role, etc.
• verb To put aside, to not act on (proposals, suggestions, advice).

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb place into a small compartment
• verb treat or classify according to a mental stereotype
• noun a small compartment
• noun a specific (often simplistic) category