/puy rim"i deen', pi-, pir"euh mi deen', -din/ , n. Biochem.
1. a heterocyclic compound, C 4 H 4 N 2 , that is the basis of several important biochemical substances.
2. one of several pyrimidine derivatives, esp. the bases cytosine, thymine, and uracil, which are fundamental constituents of nucleic acids.
[ 1880-85; b. PYRIDINE and IMIDE ]