ا س نʾ-s-n
(ض، ن) أَسَنَ يَأْسِنُasana yaʾsinu / يَأْسُنُ أُسُوْنًاyaʾsunu usūnan: (of water) to turn foul-smelling and bad-tasting from standing, to become putrid.
(س) أَسِنَ يَأْسَنُ أَسَنًاasina yaʾsanu asanan: the same meaning (the lexicographers record both); the active participles are āsin and أَسِنasin respectively.āsin (active participle (ism fāʿil)): spoiled, putrid water. Only once in the Quran: ﴿فِيْهَا أَنْهَارٌ مِّنْ مَّاءٍ غَيْرِ آسِنٍ﴾ (Muḥammad 47:15) — that is, water that never spoils.