The Collaborative International Dictionary of English v.0.48:
Uranyl \U"ra*nyl\, n. [Uranium + -yl.] (Chem.) The radical UO2, conveniently regarded as a residue of many uranium compounds. [1913 Webster]WordNet (r) 3.0 (2006):
uranyl n 1: the bivalent radical UO2 which forms salts with acids [syn: uranyl, uranyl group, uranyl radical]