Source : Webster's Revised Unabridged Dictionary (1913)

Libation \Li*ba"tion\ (l[-i]*b[=a]"sh[u^]n), n. [L. libatio, fr.
   libare to take a little from anything, to taste, to pour out
   as an offering: cf. F. libation.]
   The act of pouring a liquid or liquor, usually wine, either
   on the ground or on a victim in sacrifice, in honor of some
   deity; also, the wine or liquid thus poured out. --Dryden.

         A heathen sacrifice or libation to the earth. --Bacon.

Source : WordNet®

libation
     n 1: (facetious) a serving of an alcoholic beverage
     2: a serving (of wine) poured out in honor of a deity
     3: the act of pouring a liquid offering (especially wine) as a
        religious ceremony