م ط رm-ṭ-r
(ن) مَطَرَ يَمْطُرُ مَطْرًاmaṭara yamṭuru maṭran: (of something from the sky) to rain down. (This verb is not used in the Quran.)
مَطَرٌmaṭar (noun, ism dhāt): rain; in the Quran mostly of a rain of punishment. ﴿وَاَمْطَرْنَا عَلَيْهِمْ مَّطَرًا فَسَآءَ مَطَرُ الْمُنْذَرِيْنَ﴾ (Ash-Shuʿarāʾ 26:173)
Form IV (ifʿāl) اَمْطَرَ يُمْطِرُ اِمْطَارًاamṭara yumṭiru imṭāran: to rain down (something); مُمْطِرٌmumṭir (active participle, ism fāʿil): one who rains down. ﴿فَاَمْطِرْ عَلَيْنَا حِجَارَةً مِّنَ السَّمَآءِ﴾ (Al-Anfāl 8:32); ﴿قَالُوْا هٰذَا عَارِضٌ مُّمْطِرُنَا﴾ (Al-Aḥqāf 46:24)