im·pugn (ĭm-pyōōn') tr.v.
im·pugned, im·pugn·ing, im·pugns To attack as false or questionable; challenge in argument: impugn a political opponent's record.
[Middle English impugnen, from Old French impugner, from Latin impugnāre : in-, against; see in-2 + pugnāre, to fight; see peuk- in Indo-European roots.] im·pugn'a·ble adj., im·pugn'er n.