1.  pyrimidine(n = noun.substance) - any of several basic compounds derived from pyrimidine;
is a kind of alkali, base
has particulars: c, cytosine, t, thymine

2.  pyrimidine(n = noun.substance) - a heterocyclic organic compound with a penetrating odor;
is a kind of organic compound

pyrimidine, n.
1 Chem. an organic nitrogenous base.
2 any of a group of derivatives with similar structure, including the nucleotide constituents uracil, thymine, and cytosine.

Etymology:
G Pyrimidin f. Pyridin (as PYRIDINE, IMIDE)