methamphetamine /ˌmɛθæmˈfɛtəˌmiːn/ noun1 •A highly addictive phenethylamine stimulant drug. Its systematic (IUPAC) name is (S)-N-methyl-1-phenylpropan-2-amine.Methamphetamine is more potent than dexamphetamine which is in turn more potent than its racemate amphetamine. — 1960 formsmethamphetamines