a powerful synthetic analgesic drug which is similar to morphine in its effects but less sedative and is used as a substitute drug in the treatment of morphine and heroin addiction.
Origin:
1940s: from its chemical name, (6-di)meth(yl)a(mino-4,4-)d(iphenyl-3-heptan)one
methadone in other Oxford dictionaries
Definition of methadone in the US English dictionary
