nefandous (adj.) Look up nefandous at Dictionary.com
"not to be spoken of," 1630s, from Latin nefandous "unmentionable, impious, heinous," from ne-, negative particle, + fandus "to be spoken," gerundive of fari "to speak," from PIE root *bhā- (2) "to speak, tell, say" (see fame (n.)).