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English definition of “mercurial”

mercurial

adjective (quick)    /mɜːˈkjʊə.ri.əl/ US  /mɜːrˈkjʊr.i-/ literary
changing suddenly and often: a mercurial temperament She was entertaining but unpredictable, with mercurial mood swings.Changing frequentlyChanging intelligent, enthusiastic, and quick: a mercurial mind/witEnergetic and lively
(Definition of mercurial adjective (quick) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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