(adv.) In a false manner; erroneously; not truly; perfidiously or treacherously.

amiss apparently artificially astray beguilingly deceptively delusively erroneously factitiously fallaciously faultfully faultily in disguise in name only misleadingly mistakenly nominally ostensibly plausibly seemingly spuriously synthetically trickily truthlessly under cover of under false colors ungenuinely unnaturally untrue untruly unveraciously wrong wrongly