alkali - any of various water-soluble compounds capable of turning litmus blue and reacting with an acid to form a salt and water; "bases include oxides and hydroxides of metals and ammonia"pyridine - a toxic colorless flammable liquid organic base with a disagreeable odor; usually derived from coal purine - a colorless crystalline nitrogen-containing organic base; the parent compound of various biologically important substances purine - any of several bases that are derivatives of purine chemical compound, compound - (chemistry) a substance formed by chemical union of two or more elements or ingredients in definite proportion by weight cyanuramide, melamine - a white crystalline organic base; used mainly in making melamine resins pyrimidine - any of several basic compounds derived from pyrimidine |