noun, noun, used as a prefix
dioxide
Chemistry term used as a noun or prefix to indicate a compound with two oxygen atoms, e.g., 二酸化炭素 (carbon dioxide).
二酸化炭素は温室効果ガスの一つです。
Carbon dioxide is one of the greenhouse gases.
二酸化硫黄は火山ガスに含まれています。
Sulfur dioxide is contained in volcanic gases.
Means 'oxidation' or 'oxide' in general; 二酸化 specifies two oxygen atoms.
Compound of 二 (two) + 酸化 (oxidation), literally 'two-oxidation', a straightforward chemical naming pattern.