From The Collaborative International Dictionary of English v.0.48 [gcide]:
fountainhead \fountainhead\ n.
1. an abundant source.
Syn: well, wellspring.
[WordNet 1.5]
2. the source of water from which a stream arises.
Syn: headspring, head.
[WordNet 1.5]
From WordNet (r) 3.0 (2006) [wn]:
fountainhead
n 1: an abundant source; "she was a well of information" [syn:
well, wellspring, fountainhead]
2: the source of water from which a stream arises; "they tracked
him back toward the head of the stream" [syn: fountainhead,
headspring, head]