The Collaborative International Dictionary of English v.0.48:

Insulate \In"su*late\, v. t. [imp. & p. p. Insulated; p. pr. &
   vb. n. Insulating.] [L. insulatus insulated, fr. insula
   island. See Isle, and cf. Isolate.]
   [1913 Webster]
   1. To make an island of. [Obs.] --Pennant.
      [1913 Webster]

   2. To place in a detached situation, or in a state having no
      communication with surrounding objects; to isolate; to
      separate.
      [1913 Webster]

   3. (Elec. & Thermotics) To prevent the transfer of
      electricity or heat to or from (bodies) by the
      interposition of nonconductors.
      [1913 Webster]

   Insulating stool (Elec.), a stool with legs of glass or
      some other nonconductor of electricity, used for
      insulating a person or any object placed upon it.
      [1913 Webster]

WordNet (r) 3.0 (2006):

insulate
    v 1: protect from heat, cold, or noise by surrounding with
         insulating material; "We had his bedroom insulated before
         winter came"
    2: place or set apart; "They isolated the political prisoners
       from the other inmates" [syn: isolate, insulate]