/ ˈsɔːnə; NAmE ; ˈsaʊnə/ noun
a period of time in which you sit or lie in a small room (also called a sauna ) which has been heated to a very high temperature by burning coal or wood. Some saunas involve the use of steam :
a hotel with a swimming pool and sauna
to have / take a sauna
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WORD ORIGIN
late 19th cent.: from Finnish .