The Collaborative International Dictionary of English v.0.48:

Earmark \Ear"mark`\ ([=e]r"m[aum]rk`), n.
   1. A mark on the ear of sheep, oxen, dogs, etc., as by
      cropping or slitting.
      [1913 Webster]

   2. A mark for identification; a distinguishing mark.
      [1913 Webster]

            Money is said to have no earmark.     --Wharton.
      [1913 Webster]

            Flying, he [a slave] should be described by the
            rounding of his head, and his earmark. --Robynson
                                                  (More's
                                                  Utopia).
      [1913 Webster]

            A set of intellectual ideas . . . have earmarks upon
            them, no tokens of a particular proprietor.
                                                  --Burrow.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Earmark \Ear"mark`\, v. t. [imp. & p. p. Earmarked; p. pr. &
   vb. n. Earmarking.]
   1. To mark, as sheep, by cropping or slitting the ear.
      [1913 Webster]

   2. To designate or reserve for a specific purpose; as, the
      alumni fund was earmarked for dormitory construction.
      [PJC]

WordNet (r) 3.0 (2006):

earmark
    n 1: identification mark on the ear of a domestic animal
    2: a distinctive characteristic or attribute [syn: hallmark,
       trademark, earmark, stylemark]
    v 1: give or assign a resource to a particular person or cause;
         "I will earmark this money for your research"; "She sets
         aside time for meditation every day" [syn: allow,
         appropriate, earmark, set aside, reserve]