/ Dictionary / Index B byssus: Meaning and Definition of Find definitions for: bys•sus Pronunciation: (bis'us), [key] — pl. bys•sus•es, bys•si a collection of silky filaments by which certain mollusks attach themselves to rocks. an ancient cloth, thought to be of linen, cotton, or silk. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: byssus (Thesaurus) byssinosis bystander Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language