Fid
to trust, believe
Diffident
shy; not asertive
Fidelity
Faithfulness; loyalty
Fall
to decieve
Confide
To trust( another) with information or a secret
Fallacy
a misleading or mistaken idea
Fallacious
Misleading or deceptive
Fallible
capable of being mistaken; imperfect
Cred
to trust, believe
Credence
trust or belief
Credible
Able to be trusted in or believed
Credulity
Tendency to believe things too quickly or easily
Incredulous
unable to believe something; amazed
Dub
doubtful; to doubt
Dubious
Uncertain; doubtful
Indubitable
Certain beyond doubt or questions