Meaning : Beyond doubt or reproach.
Example :
An unimpeachable source.
Meaning : Free of guilt. Not subject to blame.
Example :
Has lived a blameless life.
Of irreproachable character.
An unimpeachable reputation.
Synonyms : blameless, inculpable, irreproachable
Meaning : Completely acceptable. Not open to exception or reproach.
Example :
Two unexceptionable witnesses.
A judge's ethics should be unexceptionable.
Synonyms : unexceptionable