1.  purine(n = noun.substance) - any of several bases that are derivatives of purine;
is a kind of alkali, base
has particulars: a, adenine, g, guanine

2.  purine(n = noun.substance) - a colorless crystalline organic base containing nitrogen; the parent compound of various biologically important substances;
is a kind of alkali, base

purine, n.
1 Chem. an organic nitrogenous base forming uric acid on oxidation.
2 any of a group of derivatives with purine-like structure, including the nucleotide constituents adenine and guanine.

Etymology:
G Purin L purus pure + uricum uric acid + -in -INE(4)