- unimpeachable - beyond doubt or reproach; "an unimpeachable source"
Antonym: questionable (indirect, via unquestionable)
- blameless, inculpable, irreproachable, unimpeachable - free of guilt; not subject to blame; "has lived a blameless life"; "of irreproachable character"; "an unimpeachable reputation"
Antonym: guilty (indirect, via innocent)
- unexceptionable, unimpeachable - completely acceptable; not open to exception or reproach; "two unexceptionable witnesses"; "a judge's ethics should be unexceptionable"
Antonym: unacceptable (indirect, via acceptable)