(ن) ثَقَلَ يَثْقُلُ ثَقْلًاthaqala yathqulu thaqlan: to lift in the hand to find out the weight.
ثِقْلٌthiql pl. اَثْقَالٌathqāl (noun, ism dhāt): weight, burden. ﴿وَاَخْرَجَتِ الْاَرْضُ اَثْقَالَهَا﴾ (Az-Zalzalah 99:2)
مِثْقَالٌmithqāl (noun of instrument, ism ālah): weights for weighing, a weight; of equal weight. ﴿فَمَنْ يَّعْمَلْ مِثْقَالَ ذَرَّةٍ خَيْرًا يَّرَهُۥ﴾ (Az-Zalzalah 99:7)
(ک) ثَقُلَ يَثْقُلُ ثِقَلًا وَثَقَالَةًthaqula yathqulu thiqalan wa-thaqālatan: to be weighty, to be heavy. ﴿فَمَنْ ثَقُلَتْ مَوَازِيْنُهُۥ﴾ (Al-Muʾminūn 23:102)
ثَقِيْلٌthaqīl pl. ثِقَالٌthiqāl (adjective on the pattern فَعِيْلٌfaʿīl): weighty, heavy. ﴿اِنَّا سَنُلْقِيْ عَلَيْكَ قَوْلًا ثَقِيْلًا﴾ (Al-Muzzammil 73:5); ﴿اِنْفِرُوْا خِفَافًا وَّثِقَالًا﴾ (At-Tawbah 9:41)
Form IV (ifʿāl) اَثْقَلَ يُثْقِلُ اِثْقَالًاathqala yuthqilu ithqālan: to make someone heavy, to load a burden on someone. ﴿فَلَمَّآ اَثْقَلَتْ دَّعَوَا اللّٰهَ رَبَّهُمَا﴾ (Al-Aʿrāf 7:189)
مُثْقَلٌmuthqal (passive participle, ism mafʿūl): laden, weighed down under a burden. ﴿فَهُمْ مِّنْ مَّغْرَمٍ مُّثْقَلُوْنَ﴾ (Aṭ-Ṭūr 52:40)
Form VI (tafāʿul) تَثَاقَلَ يَتَثَاقَلُ تَثَاقُلًاtathāqala yatathāqalu tathāqulan (original form) → اِثَّاقَلَ يَثَّاقَلُ اِثَّاقُلًاiththāqala yaththāqalu iththāqulan (form in use): to lean to one side because of a burden, to incline, to fall down. ﴿اثَّاقَلْتُمْ اِلَي الْاَرْضِ﴾ (At-Tawbah 9:38)