柯林斯詞典nitrous oxide 1. N a colourless nonflammable slightly soluble gas with a sweet smell: used as an anaesthetic in dentistry and surgery. Formula: N2O 一氧化二氮 (Systematic name dinitrogen oxideAlso called laughing gas) 返回 nitrous oxide劍橋詞典a type of gas with a sweet smell that is used as a weak anaesthetic (= substance that stops pain ), especially by dentists 一氧化二氮；笑氣（一種帶甜味的氣躰，有輕微的麻醉作用，常用於牙科止疼） 返回 nitrous oxide