As opposed to the Latin ("lawful") fas, it comes from nefas ("illegal"), they were the days that was permitted or forbidden to negotiate, the latter could also be mourning and were considered to be sad, negative, bad.
It means causing much grief, pain or sadness. It is a qualifying adjective that means disastrous, disastrous, unfortunate, tragic, hapless, unfortunate, unhappy, lousy, unfortunate, unhappy.
NEFARIOUS: UNFORTUNATE, FATAL.SAD, NEGATIVE, GLOOMY.
Unpleasant undesirable person osea a slag
Etymologically means something forbidden or unlawful