undeceivable (adjective) infallible: unerring, dependable
Sinonime: acceptable,
accurate,
agreeable, apodictic,
authoritative,
certain,
correct,
effective,
effectual,
efficacious,
efficient,
exact, faultless,
flawless, foolproof,
handy,
helpful,
impeccable,
incontrovertible, inerrable, inerrant,
omniscient,
perfect,
positive,
reliable,
satisfactory,
satisfying,
sure, surefire,
true,
trustworthy,
unbeatable, undeceivable, unfailing, unimpeachable, unquestionable,
usefulAntonime: erring, fallible,
faulty,
imperfect