/ tɔːˈneɪdəʊ; NAmE tɔːrˈneɪdoʊ/ noun
( pl. -oes or -os ) a violent storm with very strong winds which move in a circle. There is often also a long cloud which is narrower at the bottom than the top.
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WORD ORIGIN
mid 16th cent. (denoting a violent thunderstorm of the tropical Atlantic Ocean): perhaps an alteration of Spanish tronada thunderstorm (from tronar to thunder) by association with Spanish tornar to turn.