fuci
Webster's Dictionary (GCIDE)
Fucus \Fu"cus\, n.; pl. Fuci. [L. rock lichen, orchil, used as a red dye, red or purple color, disguise, deceit.]
1.A paint; a dye; also, false show. [Obs.] [1913 Webster]
2.(Bot.) A genus of tough, leathery seaweeds, usually of a dull brownish green color; rockweed. [1913 Webster]
Note: Formerly most marine alg[ae] were called fuci. [1913 Webster]