nitrous oxide
an analgesic gas that is commonly used in outpatient dental procedures and as an adjunct in surgical anesthesia. It is also used as a propellant in aerosolized foods (e.g., whipped cream). In low doses, nitrous oxide produces sensations of giddiness, elation, and euphoria. This property was apparent when it was initially synthesized in 1772 by British chemist Joseph Priestley (1733–1804), and nitrous oxide has long been known colloquially as laughing gas. Its euphoriant effects make nitrous oxide a popular inhalant in social settings. Also called dinitrogen monoxide.