periactin periacinous • periactus · · · Info · Definitions · Synonyms · Characters · · periactin · · Text Latin · · Script 9 · · Length 4 · · Syllables Definitions · · · (noun) an antihistamine (trade name Periactin) used to treat some allergic reactions. Synonyms: cyproheptadine, Periactin. · · Noun Definition 1 Synonyms · · · cyproheptadine · · Synonym 1 Characters · · a latin small letter a U+0061 c latin small letter c U+0063 e latin small letter e U+0065 i latin small letter i U+0069 n latin small letter n U+006E p latin small letter p U+0070 r latin small letter r U+0072 t latin small letter t U+0074