thymidine thy·mi·dine (thī'mĭ-dēn')
A nucleoside composed of thymine and deoxyribose.
A nucleoside composed of thymine and deoxyribose that (with the addition of phosphate to form the nucleotide thymine) occurs in DNA. Radioactively tagged thymidine has been used in genetics research to study DNA synthesis in the nuclei of cells undergoing cell division. Chemical formula: C10H14N2O5.