ن ک ثn-k-th
(ن، ض) نَكَثَ يَنْكُثُ وَيَنْكِثُ نَكْثًاnakatha yankuthu wa-yankithu nakthan: to unravel a blanket or a twisted rope, to pull yarn apart into fibres; then, to break a covenant. ﴿فَمَنْ نَّكَثَ فَاِنَّمَا يَنْكُثُ عَلٰى نَفْسِهِۦ﴾ (Al-Fatḥ 48:10); ﴿فَلَمَّا كَشَفْنَا عَنْهُمُ الْعَذَابَ اِذَا هُمْ يَنْكُثُوْنَ﴾ (Az-Zukhruf 43:50)
نِكْثٌnikth pl. اَنْكَاثٌankāth (noun, ism dhāt): unravelled blanket or yarn, thread picked to shreds. Only once in the Quran: ﴿كَالَّتِيْ نَقَضَتْ غَزْلَهَا مِنْۢ بَعْدِ قُوَّةٍ اَنْكَاثًا﴾ (An-Naḥl 16:92)