二氧化氮 èryǎnghuàdàn nitrogen 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)氮 dàn noun nitrogen the nonmetallic chemical element with symbol N; a colorless, odorless gas that makes up about four-fifths of the earth's atmosphere