OXFORD DICTIONARY
, n.
1 any of various species of small marine crustaceans of the class Cirripedia which in adult form cling to rocks, ships' bottoms, etc.
2 a tenacious attendant or follower who cannot easily be shaken off.
barnacle goose an Arctic goose, Branta leucopsis, which visits Britain in winter.
barnacled adj.
ME bernak (= med.L bernaca), of unkn. orig.
THESAURUS
adherent, adhesive, beat, bloodsucker, bramble, brier, bulldog, burr, cement, deadbeat, decal, decalcomania, freeloader, glue, gunk, hanger-on, leech, limpet, lounge lizard, molasses, mucilage, parasite, paste, plaster, prickle, remora, smell-feast, spiv, sponge, sponger, sticker, sucker, syrup, thorn