From Longman Dictionary of Contemporary Englishfountainheadfoun‧tain‧head /ˈfaʊntənhed $ ˈfaʊntn-/ noun [singular] COME FROM/ORIGINATEthe origin of something SYN source
Examples from the Corpus
fountainhead• Keynes, as we shall see presently, was on his way to being the new fountainhead of conventional wisdom.• Aunt Tossie was the fountainhead of both, the medium through which Dada might be approached for favours. 