/ ˈθɪərəm; NAmE ˈθiːə-; ˈθɪr-/ noun
( technical ) a rule or principle, especially in mathematics, that can be proved to be true
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WORD ORIGIN
mid 16th cent.: from French théorème , or via late Latin from Greek theōrēma speculation, proposition, from theōrein look at, from theōros spectator.