Mand and Cred

credulous

(adj.) too ready to believe, easily deceived

contermand

an order that revokes a previous one

credible

believable; reliable

credentials

documents, letters, references, etc., that inspire belief or trust

mandate

man authoritative command

mandatory

obligatory; required by command

acredited

officially authorized or recognized; provided with credentials

discredit

to refuse to believe; to reject as untrue

remand

to send back

incredulous

unwilling or unable to believe something