whiffle (v.) "flicker or flutter as if blown by the wind," 1660s; see whiff. The noun meaning "something light or insignificant" (1670s) is preserved in whiffle-ball (1931).
whiff (n.) 13c., weffe "foul scent or odor," of imitative origin. Modern form became popular late 16c. with tobacco smoking, probably influenced by whiffle "blow in gusts or puffs" (1560s). The verb in the baseball slang sense "to swing at a ball and miss" first recorded 1913.