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]