Root ن ح س(n H s) has 3 unique word forms and appears 3 times in the Quran.

English gloss Calamitous, Ill fated, Unlucky

Word Translation Occurrences
نَحۡسٖ (of) misfortune, (of) misfortune 2
نَّحِسَاتٖ (of) misfortune, (of) misfortune 2
وَنُحَاسٞ and smoke, and smoke 2