A nucleoside in which the sugar component is ribose; the common ribonucleosides of RNA are adenosine, cytidine, guanosine, and uridine.
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ri·bo·nu·cleo·side (ri″bo-nooґkle-o-sīd) a nucleoside in which the purine or pyrimidine base is combined with ribose.Medical dictionary. 2011.