二氧化碳 èryǎnghuàtàn HSK7 carbon dioxide Origin Definitions Defs Strokes Stroke Words Sentences Sents 二 èr numeral two the number two; 2氧化 yǎnghuà noun oxidize; oxidation to combine with oxygen; the chemical process of losing electrons (as in rusting or combustion)碳 tàn noun carbon nonmetallic element (C); the essential component of organic matter, existing in nature as diamond, graphite, and coal