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.
Phrases and idioms:
barnacle goose an Arctic goose, Branta leucopsis, which visits Britain in winter.
Derivatives:
barnacled adj.
Etymology: ME bernak ( med.L bernaca), of unkn. orig.