The Collaborative International Dictionary of English v.0.48:
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. [Webster 1913 Suppl.]WordNet (r) 3.0 (2006):
Zeitgeist n 1: the spirit of the time; the spirit characteristic of an age or generation