عُثَانٌ

Smoke; (S, Mgh, Msb, K;) as also ↓ عَثَنٌ: (S, K: [in one of my copies of the S, written with the ث quiescent:]) mostly used in relation to a substance with which one fumigates: (Mgh, Msb:) and also explained as signifying smoke without fire: (TA:) plural عَوَاثِنُ, (S, K, TA,) deviating from rule, (TA,) like دَوَاخِنُ plural of دُخَانٌ, the only other instance of the kind. (S, TA.)

And (tropical:) Dust (Az, S, Mgh, K) is sometimes thus called, (S, Mgh,) metaphorically, (Mgh,) as being likened to smoke, which is the primary meaning: so says A'Obeyd, and Aboo-'Amr Ibn-El-'Alà says the like. (Az.)