n. [ Penta- + methylene. ] (Chem.) A hypothetical hydrocarbon, C5H10, metameric with the amylenes, and the nucleus of a large number of derivatives; -- so named because regarded as composed of five methylene residues. Cf. Trimethylene, and Tetramethylene. [ 1913 Webster ]
(n) a drug used as a circulatory and respiratory stimulant; larger doses cause convulsions in shock therapy; Metrazol is a trademark, Syn. Metrazol, pentamethylenetetrazol