Definition from Wiktionary, the free dictionary
nucleotide (plural nucleotides)
- (biochemistry) the monomer comprising DNA or RNA biopolymer molecules. Each nucleotide consists of a nitrogenous heterocyclic base (or nucleobase), which can be either a double-ringed purine or a single-ringed pyrimidine; a five-carbon pentose sugar (deoxyribose in DNA or ribose in RNA); and a phosphate group.
Derived terms 
See also 
monomer comprising DNA or RNA
nucleotide m (plural nucleotidi)