The methyl radical, —CH3.
[English methylene, derived from Greek methu, wine, plus hulē, wood, because methyl alcohol was first prepared by the destructive distillation of wood.]
Meth- occurs in a variety of common names for chemical substances, many of them drugs, such as methamphetamine, a methyl derivative of amphetamine, a synthetic drug used illegally as a stimulant; methadone, used in the treatment of morphine and heroin addiction; and methicillin, a semi-synthetic form of penicillin. Examples of drug names on invented stems that include the longer form metho- are methoserpidine, used to lower blood pressure; and methotrexate, a treatment for leukaemia. Methene (see -ene1) is the systematic name for the methylene radical —CH2—; methacrylic acid is used in the manufacture of synthetic resins.