Mercurial
Mercury thermometers and certain musicians share a reputation for fast mood weather.
Learn This WordMeaning
Subject to sudden or unpredictable changes of mood or mind; volatile.
Memory trick
Mercury is the “quick-change” planet/god, mercurial things change quickly and unpredictably.
Examples
The market has been mercurial all quarter, swinging on small headlines.
His mercurial mood made it hard to know how feedback would land.
The weather turned mercurial, shifting from sun to storms in an hour.
Synonyms
Antonyms
Etymology
From Latin Mercurius (Mercury), the swift Roman messenger god; later associated with quick change and, in alchemy, with mercury metal.
Usage Notes
Works well for people, markets, trends, or conditions that change quickly. It’s more vivid and literary than “volatile.”
Real-life contexts
Use in analysis: "Demand is mercurial right now; we should run smaller experiments."
Use for behavior: "He can be mercurial, choose your timing."
Use for conditions: "The situation is mercurial, so keep plans flexible."
Common Mistakes
Don’t use mercurial to mean “fast.” It’s about unpredictability and sudden shifts.
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Part of Speech
adjective
Difficulty
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