barbitonePronunciation: /ˈbɑːbɪtəʊn/Definition of barbitone noun [mass noun] a long-acting sedative and sleep-inducing drug of the barbiturate type. Chemical formula: C6H12O3N2 Origin: early 20th century: from barbituric acid + -onebarbitone in other Oxford dictionaries Definition of barbitone in the US English dictionary