Nucleotide

• the basic building block of nucleic acids; composed of a five-carbon sugar (either ribose or deoxyribose), a phosphate, and a nitrogenous base (either a purine or pyrimidine).
  Source: Anthromorphemics
• one of the nucleic acid bases, that along with sugar and inorganic phosphate make up the basic subunits of DNA and RNA
  Source: Jenkins, John B. 1990. Human Genetics, 2nd Edition. New York: Harper & Row
• A building block of DNA and RNA, consisting of a nitrogenous base, a five-carbon sugar, and a phosphate group. Together, the nucleotides form codons, which when strung together form genes, which in turn link to form chromosomes.
• A nucleotide is the basic building block of nucleic acids. RNA and DNA are polymers made of long chains of nucleotides. A nucleotide consists of a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base. The bases used in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T). In RNA, the base uracil (U) takes the place of thymine.