Unimpeachable (adjective)

1. Beyond doubt or question, especially in terms of integrity or honesty.
2. Not capable of being challenged or criticized.
3. Free from guilt or blame.

Origin:

From un- + impeachable, from old french empecher, to hinder, from latin impedicare, to entangle.

Examples:

1. Her unimpeachable reputation for honesty and fairness is widely recognized.
2. The witnesses' testimony was unimpeachable, providing solid evidence.
3. The scientist's research results were unimpeachable, based on rigorous methodologies.
4. His unimpeachable ethics and morality are an example to others.
5. The team's victory was due to their unimpeachable teamwork and coordination.