Pebbly silk or worsted fabric with broken rib weave; worsted fabric with twill hopsack weave; silk or silk-and-worsted fabric with lightly ribbed or pebbled weave.

ETYM Latin byssus fine flax, fine linen or cotton, Greek byssos.
Tuft of strong filaments by which e.g. a mussel makes itself fast to a fixed surface; SYN. beard.
Mummy-wrapping fabric.
Filamentous tuft (“beard”) by which mollusks attach themselves; fine flax and fabric woven from it.