Bÿs'sus, n.

n. [Lat. byssus, Gr. βύσσος; fine flax, fine linen or cotton, Heb. būss.]

1. A cloth of exceedingly fine texture, used by the ancients. It is disputed whether it was of cotton, linen, or silk.
2. (Conch.) A tuft of long, delicate, lustrous, and silky filaments, which issues from the shell of certain acephalous mollusks, as the Pinna, Mytilus, &c., and by means of which they are attached to submarine bodies. Baird.
3. (Bot.) A filamentous, fungous plant, of different genera, found in cellars and other subterranean places, now ascertained to be a fungaceous plant in an early stage of growth.
4. The asbestus, a mineral composed of parallel fibers. Nicholson.