overact \| ̷ ̷ ̷ ̷| ̷ ̷\transitive verb 1.: to act or perform (as a part) to excess : exaggerate in acting 2.obsolete: to outdo in acting 3.obsolete: to act upon or influence unduly intransitive verb 1.: to act more than is necessary : go to excess in action < which muscles of the eyes are … overacting — H.G.Armstrong > 2.: to overact a part