The Collaborative International Dictionary of English v.0.48:

Contact \Con"tact\ (k[o^]n"t[a^]kt), n. [L. contactus, fr.
   contingere, -tactum, to touch on all sides. See
   Contingent.]
   1. A close union or junction of bodies; a touching or
      meeting.
      [1913 Webster]

   2. (Geom.) The property of two curves, or surfaces, which
      meet, and at the point of meeting have a common direction.
      [1913 Webster]

   3. (Mining) The plane between two adjacent bodies of
      dissimilar rock. --Raymond.
      [1913 Webster]

   4. (Electricity) A metallic conducting component of an
      electrical device connected to a circuit within and so
      situated that it may form a conducting pathway to an
      external power source or device when contacted by another
      conductor; as, the contact on a standard light bulb has
      the shape of a screw for easy insertion into the socket.
      [PJC]

   5. A person who serves to commmunicate information to or from
      one group to another, whether formally or informally; as,
      a good Washington reporter has contacts in the White
      House.
      [PJC]

   Contact level, a delicate level so pivoted as to tilt when
      two parts of a measuring apparatus come into contact with
      each other; -- used in precise determinations of lengths
      and in the accurate graduation of instruments.
      [1913 Webster]

WordNet (r) 3.0 (2006):

contact
    n 1: close interaction; "they kept in daily contact"; "they
         claimed that they had been in contact with extraterrestrial
         beings"
    2: the act of touching physically; "her fingers came in contact
       with the light switch" [syn: contact, physical contact]
    3: the state or condition of touching or of being in immediate
       proximity; "litmus paper turns red on contact with an acid"
    4: the physical coming together of two or more things; "contact
       with the pier scraped paint from the hull" [syn: contact,
       impinging, striking]
    5: a person who is in a position to give you special assistance;
       "he used his business contacts to get an introduction to the
       governor" [syn: contact, middleman]
    6: a channel for communication between groups; "he provided a
       liaison with the guerrillas" [syn: liaison, link,
       contact, inter-group communication]
    7: (electronics) a junction where things (as two electrical
       conductors) touch or are in physical contact; "they forget to
       solder the contacts" [syn: contact, tangency]
    8: a communicative interaction; "the pilot made contact with the
       base"; "he got in touch with his colleagues" [syn: contact,
       touch]
    9: a thin curved glass or plastic lens designed to fit over the
       cornea in order to correct vision or to deliver medication
       [syn: contact, contact lens]
    v 1: be in or establish communication with; "Our advertisements
         reach millions"; "He never contacted his children after he
         emigrated to Australia" [syn: reach, get through, get
         hold of, contact]
    2: be in direct physical contact with; make contact; "The two
       buildings touch"; "Their hands touched"; "The wire must not
       contact the metal cover"; "The surfaces contact at this
       point" [syn: touch, adjoin, meet, contact]