اسن1 أَسَنَ, aor. ـُ (S, M, Mgh, Msb, K) and اَسِنَ, (S, M, K,) inf. n. أُسُونٌ (S, M, Msb) and أَسْنٌ; (M;) and أَسِنَ, aor. ـَ (S, M, &c.,) inf. n. أَسَنٌ; (S, M, Msb;) said of water, i. q. أَجَنَ and أَجِنَ; (S, K;) [i. e.] It became altered for the worse (M, Mgh, Msb) in odour, (M,) [or in taste and colour, from some such cause as long standing, (see أَجَنَ,)] but was drinkable; (M;) or so as not to be drunk, (Msb, TA,) thus differing from أَجَنَ and أَجِنَ. (TA.) [See also أَصِلَ.]أَسِنٌ: see what follows.آسِنٌ (S, Mgh, Msb, K) and ↓ أَسِنٌ, (S, Mgh, Msb,) applied to water, (S, Mgh, &c.,) i. q. آجِنٌ [and أَجِنٌ]; (S, K;) [i. e.] Altered for the worse (Mgh, Msb) in odour, (Mgh,) [or in taste and colour, from some such cause as long standing but drinkable; (see above, and see آجِنٌ;)] or so as not to be drunk, (Msb, TA,) thus differing from آجِنٌ and أَجِنٌ: (TA:) pl. [of the former]آسَانٌ [like as أَطْهَارٌ is pl. of طَاهِرٌ, or perhaps it may have for its sing. أَسْنٌ, like أَجْنٌ]. (M, TA.) مَنْ مَآءٍ غَيْرِ آسِنٍ, in the Kur [xlvii. 16], is explained by Fr as meaning Of water not altered for the worse; not آجِن. (TA.)