طحلب

طُحْلُبٌ ذ and طُحْلَبٌ (S, Msb, K) and طِحْلِبٌ (Lh, M, K) The green substance, (S, K,) or green slimy substance, (Msb,) that overspreads water (S, Msb, K) which has become stale: (K:) or what is upon water, resembling the web of the spider: n. un. with ة. (TA.) [See also عَرْمَضٌ.]