Purine or pyrimidine bases attached to a ribose or deoxyribose. (From King & Stansfield, A Dictionary of Genetics, 4th ed)

Go to Biochemical Molecules Any of the various compounds consisting of a sugar, usually ribose or deoxyribose, and a purine or pyrimidine base, especially a compound obtained by hydrolysis of a nucleic acid, such as adenosine or guanine .