carbonic acid gas carbonic acid • carbonic-acid gas · · · Info · Definitions · Synonyms · Characters · · carbonic acid gas · · Text Common · · Latin · · Scripts 17 · · Length 6 · · Syllables Definitions · · · (noun) a heavy odorless colorless gas formed during respiration and by the decomposition of organic substances; absorbed from the air by plants in photosynthesis. Synonyms: carbon dioxide, CO2, carbonic acid gas. · · Noun Definition 1 Synonyms · · · carbon dioxide · · Synonym 1 co2 · · Synonym 2 Characters · · space U+0020 a latin small letter a U+0061 b latin small letter b U+0062 c latin small letter c U+0063 d latin small letter d U+0064 g latin small letter g U+0067 i latin small letter i U+0069 n latin small letter n U+006E o latin small letter o U+006F r latin small letter r U+0072 s latin small letter s U+0073