Mercurial

mər-KYUR-ee-uhl (or mur-KYOOR-ee-uhl)

Definition

  1. (adjective) Subject to sudden or unpredictable changes of mood or mind; volatile, capricious.
  2. Relating to the Roman god Mercury (or the planet Mercury), often implying qualities of cleverness, eloquence, or swiftness.

Example

Her mercurial temperament made her both exhilarating and exhausting to work with; one moment she was full of boundless enthusiasm, and the next, stormy and withdrawn.

Fun Fact

The word “mercurial” is derived from the Roman god Mercury, who was known for his speed, wit, and trickery. Mercury was also the messenger of the gods, and his unpredictable nature made him a fitting inspiration for the term. In alchemy, “mercurial” also refers to mercury (quicksilver), a liquid metal known for its fluid and volatile properties, reinforcing the word’s association with changeability. Over time, “mercurial” evolved to describe not only physical but also emotional and mental shifts, making it a vivid way to characterize people with ever-changing moods.