Definition of Pyrimidine Pyrimidine: One of the two classes of bases in DNA and RNA. The pyrimidine bases are thymine (T) and cytosine (C) in DNA and cytosine (C) and uracil (U) in RNA.
Pyrimidine: One of the two classes of bases in DNA and RNA. The pyrimidine bases are thymine (T) and cytosine (C) in DNA and cytosine (C) and uracil (U) in RNA.
