“As a child she was calm and even-keeled, but, as a teen, she became mercurial: her friends and family members never knew what to expect.”

As used in the above sentence, what is the best meaning for mercurial?

Check your answer!

Choice A - Related to the planet mercury
Choice B - Experiencing extreme fluctuations in body temperature
Choice C - Characterized by rapid changes in mood
Choice D - Usually exhibiting bitter and disdainful behavior


Mercurial (adjective) – characterized by sudden, unpredictable, or extreme changes of the mood or of the mind; or, less commonly, having characteristics similar to the Roman god Mercury (i.e. being clever and eloquent but cunning)

GRE pro tips:

Although there are a few definitions of the word mercurial, the most common and the most likely to show up on the GRE is: rapidly and unpredictably changing, particularly in mood or in mind. You can better remember this definition by relating it to the planet Mercury. Unlike earth, Mercury has a thin atmosphere, so it’s susceptible to rapid, extreme fluctuations in temperature (between -279 and +809 degrees Fahrenheit!). Likewise, someone with a “mercurial” disposition could suddenly switch from hot to cold, or happy to sad, or sweet to angry. Think of moody like Mercury to remember this word.

Example sentences:

“Unlike her sister, who was consistently level-headed and calm, Mary had a rather mercurial disposition.”

“Although my overall preferences for Netflix bingeing are mercurial, I am always up for watching The Office.”