not likely

absurd implausible improbable inconceivable incredible rare remote strange unbelievable

contrary doubtful dubious faint out of the ordinary outside chance questionable slight unconvincing unheard-of unimaginable untoward

believable common credible likely plausible possible probable reasonable regular tenable usual

imaginable probably

barely comparatively practically rarely seldom simply somewhat

just

almost inconceivably almost not by a hair by no means detectably faintly gradually imperceptibly infrequently little no more than no way not a bit not at all not by much not markedly not measurably not much not notably not noticeably not often not quite once in a blue moon only only just perceptibly pretty near scantly slightly sparsely sporadically with trouble

frequently

very