The Collaborative International Dictionary
Nefand \Ne"fand\, Nefandous \Ne*fan"dous\, a. [L. nefandus not
to be spoken; ne not + fari to speak.]
Unfit to speak of; unmentionable; impious; execrable. [Obs.]
``Nefand adominations.''
--Sheldon. ``Nefandous high
treason.''
--Cotton Mather.
Douglas Harper's Etymology Dictionary
"not to be spoken of," 1630s, from Latin nefandous "unmentionable, impious, heinous," from ne-, negative particle, + fandus "to be spoken," gerundive of fari (see fame (n.)).
Wiktionary
a. unspeakable, appalling.
Usage examples of "nefandous".
He had been brought very close to that immane and nefandous Burke-and-Hare business which made the blood of civilization run cold in the year 1828, and told me, in a very calm way, with an occasional pinch from the mull, to refresh his memory, some of the details of those frightful murders, never rivalled in horror until the wretch Dumollard, who kept a private cemetery for his victims, was dragged into the light of day.
Many of the persons who held such opinions were, of course, guilty of the most nefandous conduct themselves, and yet saw no paradox in holding such views because they were not hypocrites themselves-they took no moral stances and lived by none.
It had only horror, because I knew unerringly the monstrous, nefandous analogy that had suggested it.
Only the bricks of the chimney, the stones of the cellar, some mineral and metallic litter here and there, and the rim of that nefandous well.