incontestable

absolute ascertained authoritative clear conclusive confirmable definite demonstrable destined determined establishable evident firm fixed genuine guaranteed hard having down pat in the bag inarguable incontrovertible indisputable indubitable infallible irrefutable known on ice plain positive predestined provable real reliable safe salted away set sound supreme sure sure thing true trustworthy unambiguous unassailable undeniable undisputable undoubted unequivocal unerring unmistakable unquestionable verifiable