Same word as unaccountably:

abnormally, above all, before all else, chiefly, conspicuously, curiously, eminently, exclusively, expressly, extraordinarily, in particular, in specie, mainly, markedly, notably, oddly, outstandingly, peculiarly, preeminently, primarily, principally, remarkably, signally, singularly, specially, specifically, strangely, strikingly, supremely, unaccountably, uncommonly, uncustomarily, uniquely, unusually, wonderfully