WordNet sense 1 (hidden on any grounds for any motive):

concealed

WordNet sense 2 (established irrevocably):

certain

WordNet sense 3 (incapable of being retracted or revoked):

irrevocable, irrevokable

WordNet sense 4 ((of walls) covered with a coat of plaster):

plastered

WordNet sense 5 (overlaid or spread or topped with or enclosed within something; sometimes used as a combining form):

covered