What is the definition for mercurial in Greek mythology?

The term "mercurial" in Greek mythology doesn't have a direct equivalent. It's an adjective derived from the Roman god Mercury, who is the equivalent of the Greek god Hermes.

"Mercurial" is used to describe someone or something that is:

* Quick-witted and clever: This reflects Hermes's role as a messenger and trickster god, known for his cunning and speed.

* Changeable and unpredictable: This relates to Hermes's ability to move quickly and easily between different places and situations, as well as his mischievous nature.

* Lively and animated: This reflects Hermes's energetic and playful personality.

Therefore, when referring to a character or concept in Greek mythology, you'd use Hermes and his attributes to describe traits similar to what "mercurial" signifies in English.