unimpeachable
adjective
1. beyond doubt or reproach
- an unimpeachable source
Similar word(s): unquestionable
2. free of guilt; not subject to blame
- an unimpeachable reputation
Similar word(s): guiltless, innocent, blameless, inculpable, irreproachable
3. completely acceptable; not open to exception or reproach
Similar word(s): acceptable, unexceptionable