Old English gedæfte "gentle, becoming," from Proto-Germanic *gadaftjaz (cognates: Old English daeftan "to put in order, arrange," gedafen "suitable;" Gothic gadaban "to be fit"), from PIE *dhabh- "to fit together" (see fabric). Sense of "mild, well-mannered" (c.1200) led to that of "dull, awkward" (c.1300). Further evolution to "foolish" (mid-15c.), "crazy" (1530s) probably was influenced by analogy with daffe "halfwit" (see daffy); the whole group probably has a common origin.