mercurial
UK: /mɜːˈkjʊə.ri.əl/ | US: /mɜːrˈkjʊr.i.əl/
adj. 1. (of a person) prone to sudden changes in mood or behavior; unpredictable.
adj. 2. relating to the planet Mercury or the Roman god Mercury.
adj. 3. (archaic) containing or caused by mercury (the metal).
Derived from Latin Mercurialis, referring to the Roman god Mercury, known for his speed and elusiveness as the messenger of the gods. The adjective evolved to describe qualities associated with Mercury—swiftness, volatility (like the metal mercury/quicksilver), and unpredictability. Over time, it shifted from literal associations (e.g., planetary or metallic traits) to figurative use for capricious human behavior.
Her mercurial temperament made her both fascinating and hard to predict.
The artist’s mercurial genius led to rapid shifts in style.
Ancient alchemists studied mercurial substances for their transformative properties.
The stock market’s mercurial nature demands cautious investing.
His mercurial wit kept the audience constantly surprised.