pyrimidone in English dictionary pyrimidone Meanings and definitions of "pyrimidone" noun (organic chemistry) Either of two heterocyclic compounds, with chemical formula C 4H 4N 2O, whose derivatives are the basis of many other biological molecules. more Grammar and declension of pyrimidone pyrimidone (countable and uncountable, plural pyrimidones) more Sample sentences with "pyrimidone" Declension Stem Try again Authors