'methadone' originates from German, specifically the word 'Methadon,' which was derived from the chemical name '6-(dimethylamino)-4,4-diphenylheptan-3-one.'

'Methadon' was adopted into English as 'methadone' in the mid-20th century, and eventually became the modern English word 'methadone.'

Initially, it referred specifically to the synthetic opioid compound, and this meaning has remained consistent in modern usage.