Dastardly rhymes with:
awkwardly, cowardly, downwardly, good-naturedly, haphazardly, inwardly, naturedly, niggardly, northwardly, outwardly, straightforwardly, upwardly
awkwardly, cowardly, downwardly, good-naturedly, haphazardly, inwardly, naturedly, niggardly, northwardly, outwardly, straightforwardly, upwardly