The Collaborative International Dictionary of English v.0.48:

Cider \Ci"der\, n. [F. cidre, OF. sidre, fr. L. sicera a kind of
   strong drink, Gr. ?; of Oriental origin; cf. Heb. sh[=a]kar
   to be intoxicated, sh[=e]k[=a]r strong drink.]
   The expressed juice of apples. It is used as a beverage, for
   making vinegar, and for other purposes.
   [1913 Webster]

   Note: Cider was formerly used to signify the juice of other
         fruits, and other kinds of strong liquor, but was not
         applied to wine.
         [1913 Webster]

   Cider brandy, a kind of brandy distilled from cider.

   Cider mill, a mill in which cider is made.

   Cider press, the press of a cider mill.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cider
    n 1: a beverage made from juice pressed from apples [syn:
         cider, cyder]