phenobarbital phenmiazine • phenobarbital sodium · · · Info · Definitions · Synonyms · Characters · · phenobarbital · · Text Latin · · Script 13 · · Length 5 · · Syllables Definitions · · · (noun) a long-acting barbiturate used as a sedative. Synonyms: sodium thiopental, phenobarbitone, Luminal, purple heart. · · Noun Definition 1 Synonyms · · · sodium thiopental · · Synonym 1 phenobarbitone · · Synonym 2 luminal · · Synonym 3 purple heart · · Synonym 4 Characters · · a latin small letter a U+0061 b latin small letter b U+0062 e latin small letter e U+0065 h latin small letter h U+0068 i latin small letter i U+0069 l latin small letter l U+006C n latin small letter n U+006E o latin small letter o U+006F p latin small letter p U+0070 r latin small letter r U+0072 t latin small letter t U+0074