Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
co2 is a noun meaning "a heavy odorless colorless gas formed during respiration and by the decomposition of organic substances; absorbed from the air by plants in photosynthesis". It carries one recorded sense.
a heavy odorless colorless gas formed during respiration and by the decomposition of organic substances; absorbed from the air by plants in photosynthesis
Definitions, synonyms and semantic relations for co2 come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.