- any of the class of compounds derived by the hydrolysis of nucleic acids or nucleotides, consisting typically of deoxyribose or ribose combined with adenine, guanine, cytosine, uracil, or thymine.
- biochem a compound containing a purine or pyrimidine base linked to a sugar (usually ribose or deoxyribose)
- Any of 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.
- Any of various compounds consisting of a sugar, usually ribose or deoxyribose, and a nitrogen base (a purine or pyrimidine). Nucleosides are constituents of the nucleotides of nucleic acids. Adenosine and thymidine are nucleosides.