Deoxyribonucleic Acid (DNA) contains four nucleotide bases.
Note that adenosine and guanosine are both purines, and thymidine and cytidine are pyrimidines. A pairs with T, and G pairs with C.
Often the base pairs are referred to as A-T or G-C basepairs (bps), or adenine to thymine and gunanine to cytosine. Rarely do people or textbooks use the full names of the nucleotides (adenosine, thymidine, guanosine, cytidine).