¹ Source: wiktionary.com
Medical Definition of Ribosyl
1. The radical formed by loss of the hemiacetal OH group from either of the two cyclic forms of ribose (yielding ribofuranosyl and ribopyranosyl compounds), by combination with an H of an -NH-or a -CH-group; the natural nucleosides are ribosyl compounds, not ribosides, as the bond between ribose and aglycon is C-N or C-C, not -C-O-X-. (05 Mar 2000)