- a colorless, sweet-smelling, sweet-tasting, nonflammable, slightly water-soluble gas, N2O, that sometimes produces a feeling of exhilaration when inhaled: used chiefly as an anesthetic in dentistry and surgery, in the manufacture of chemicals, and as an aerosol.
- a colourless nonflammable slightly soluble gas with a sweet smell: used as an anaesthetic in dentistry and surgery. Formula: N 2 O
