What does "unimpeachable" mean?

Unimpeachable: Not impeachable; not to be called in question; exempt from liability to accusation; free from stain, guilt, or fault; irreproachable; blameless; as, an unimpeachable reputation; unimpeachable testimony. Burke. -- Un`im*peach"a*ble*ness, n. -- Un`im*peach"a*bly, adv.

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