The Collaborative International Dictionary of English v.0.48:

Pigeonhole \Pi"geon*hole`\, v. t.
   To place in the pigeonhole of a case or cabinet; hence, to
   put away; to lay aside indefinitely; as, to pigeonhole a
   letter or a report.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pigeonhole \Pi"geon*hole`\, n.
   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. --Burke.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pigeonhole
    n 1: a specific (often simplistic) category
    2: a small compartment [syn: cubbyhole, pigeonhole]
    v 1: place into a small compartment
    2: treat or classify according to a mental stereotype; "I was
       stereotyped as a lazy Southern European" [syn: pigeonhole,
       stereotype, stamp]