طُحْلُبٌ

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.]