Entries linking to feyness
"of excitement that presages death," from Old English fæge "doomed to die, fated, destined," also "timid, feeble;" and/or from Old Norse feigr, both from Proto-Germanic *faigjo- (source also of Old Saxon fegi, Old Frisian fai, Middle Dutch vege, Middle High German veige "doomed," also "timid," German feige "cowardly"), from the same source as foe. Preserved in Scottish. Sense of "displaying unearthly qualities" and "disordered in the mind (like one about to die)" led to modern ironic sense of "affected."
word-forming element denoting action, quality, or state, attached to an adjective or past participle to form an abstract noun, from Old English -nes(s), from Proto-Germanic *in-assu- (cognates: Old Saxon -nissi, Middle Dutch -nisse, Dutch -nis, Old High German -nissa, German -nis, Gothic -inassus), from *-in-, originally belonging to the noun stem, + *-assu-, abstract noun suffix, probably from the same root as Latin -tudo (see -tude).