Source : Webster's Revised Unabridged Dictionary (1913)

Zeitgeist \Zeit"geist`\, n. [G.; zeit time + geist spirit. See
   {Tide}, n.; {Ghost}, n.]
   The spirit of the time; the general intellectual and moral
   state or temper characteristic of any period of time.

Source : WordNet®

Zeitgeist
     n : the spirit of the time; the spirit characteristic of an age
         or generation