Unimpeachable \Un`im*peach"a*ble\, a.
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.
[1913 Webster]