n. The typical genus of Sabellidæ, containing large tubicolous cephalobranchiate marine annelids or sea-worms, with feathery or fan-like gills of remarkable delicacy and brilliancy, and greenish blood. See cut under cerebral.n. [lowercase] A worm of this genus, or any member of the Sabellidæ: as, the fan-sabella, S. penicillus.