ن ح سn-ḥ-s
(ف، س) نَحَسَ يَنْحَسُ وَنَحِسَ يَنْحَسُ نَحْسًاnaḥasa yanḥasu wa-naḥisa yanḥasu naḥsan: to be ill-omened, to be inauspicious — the opposite of سَعْدsaʿd. (This verb is not used in the Quran.)
نَحْسٌnaḥs pl. نَحِسَاتٌnaḥisāt (verbal noun, maṣdar, also an adjective): ill omen; ill-omened. ﴿فِيْ يَوْمِ نَحْسٍ مُّسْتَمِرٍّ﴾ (Al-Qamar 54:19); ﴿فِيْٓ اَيَّامٍ نَّحِسَاتٍ﴾ (Fuṣṣilat 41:16)
نُحَاسٌnuḥās (noun, ism dhāt): (molten) copper; some have said flameless smoke. Only once in the Quran: ﴿يُرْسَلُ عَلَيْكُمَا شُوَاظٌ مِّنْ نَّارٍ وَّنُحَاسٌ﴾ (Ar-Raḥmān 55:35)