The Collaborative International Dictionary of English v.0.48:
Radiantly \Ra"di*ant*ly\ (r[=a]"d[i^]*ant*l[y^]), adv. In a radiant manner; with glittering splendor. [1913 Webster]WordNet (r) 3.0 (2006):
radiantly adv 1: in a radiant manner; "the bride smiled radiantly"