Byssus (&unr_;), n.; pl. E. Byssuses (&unr_;); L. Byssi. (&unr_;) [L. byssus fine flax, fine linen or cotton, Gr. byssos .]
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1. A cloth of exceedingly fine texture, used by the ancients. It is disputed whether it was of cotton, linen, or silk. [Written also byss and byssin.]
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2. (Zoöl.) A tuft of long, tough filaments which are formed in a groove of the foot, and issue from between the valves of certain bivalve mollusks, as the Pinna and Mytilus, by which they attach themselves to rocks, etc.
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3. (Bot.) An obsolete name for certain fungi composed of slender threads.
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4. Asbestus.
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