[bys.sus] n, pl bys.sus.es or bys.si [ME bissus, fr. L byssus, fr. Gk byssos flax, of Sem origin; akin to Heb bus linen cloth] (14c) 1: a fine prob. linen cloth of ancient times
2. [NL, fr. L]: a tuft of long tough filaments by which some bivalve mollusks (as mussels) adhere to a surface