spa: [17] The town of Spa, in eastern Belgium, has medicinal mineral springs. They were discovered in the 14th century, and by the early 17th century were well enough known in Britain for the town’s name to be used as a generic term for ‘medicinal springs’. The present-day application to a ‘town containing such springs’ emerged towards the end of the 18th century. [spa etymology, spa origin, 英语词源]