Thymidine
= Thymidine
<Thymidine> conventionally means the nucleoside containing thymine and deoxyribose. Its phosphorylated derivatives supply thymidine nucleotides for DNA metabolism.
The sugar identity matters: ribothymidine contains ribose instead. Distinguishing base, nucleoside, and nucleotide prevents a change in phosphate content from being hidden by an imprecise name.