The Collaborative International Dictionary of English v.0.48:

Lubricate \Lu"bri*cate\, v. t. [L. lubricatus, p. p. of
   lubricare to lubricate. See Lubric.]
   1. To make smooth or slippery; as, mucilaginous and
      saponaceous remedies lubricate the parts to which they are
      applied. --S. Sharp.
      [1913 Webster]

            Supples, lubricates, and keeps in play,
            The various movements of this nice machine. --Young.
      [1913 Webster]

   2. To apply a lubricant to, as oil or tallow.
      [1913 Webster]

   3. Hence: To reduce social frictions or difficulties between
      people, thus making cooperation easier and joint action
      smoother.
      [PJC]

   4. To inebriate by supplying with alcoholic beverages.
      [slang]
      [PJC]

WordNet (r) 3.0 (2006):

lubricate
    v 1: have lubricating properties; "the liquid in this can
         lubricates well"
    2: apply a lubricant to; "lubricate my car" [syn: lubricate,
       lube]
    3: make slippery or smooth through the application of a
       lubricant; "lubricate the key"