Fu"cus (?), n.; pl. Fuci (#). [L. rock lichen, orchil, used as a red dye, red or purple color, disguise, deceit.]
A paint; a dye; also, false show.
A genus of tough, leathery seaweeds, usually of a dull brownish green color; rockweed.
⇒ Formerly most marine algae were called fuci.
© Webster 1913.