noun
The chemical element oxygen (O). Used in scientific, medical, and everyday contexts.
水は水素と酸素からできている。
Water is made of hydrogen and oxygen.
酸素マスクをつけてください。
Please put on an oxygen mask.
Coined in Japan during the Meiji period as a calque of the Western scientific term 'oxygen'. 酸 (acid) + 素 (element), reflecting the early belief that oxygen was the essential component of acids.