/pen"tayn/ , n. Chem., Pharm.
1. a hydrocarbon of the methane series, existing in three liquid isomeric forms.
2. Also called normal pentane . the most important isomer of pentane, a colorless, flammable, water-insoluble, very volatile liquid, C 5 H 12 , obtained from petroleum by distillation: used chiefly as a solvent and in medicine as an anesthetic.
[ 1875-80; PENT- + -ANE ]