Meaning

noun an interest followed with exaggerated zeal

originOf English dialectal origin. Further origin obscure. Possibly from Old English ġefæd (“order, decorum”) (compare Old English ġefæd (“orderly, tidy”), fadian, ġefadian (“to set in order, arrange”), whence Middle English faden (“to arrange”)); or from French fadaise ("a trifling thought"; see fadaise).

Etymology from Wiktionary, CC BY-SA 3.0