Which word describes a person who frequently shifts their mood or temperament?

The term that describes a person who frequently shifts their mood or temperament is "mercurial." This word originates from Mercury, the Roman god of speed and eloquence, and it captures the essence of someone whose emotions are changeable and unpredictable. Individuals described as mercurial often exhibit a wide range of emotions in a short period, shifting from one mood to another. This characteristic is particularly notable in certain contexts, such as in various artistic expressions or in dynamic personality types, where emotional responses can vary dramatically based on circumstances.

On the other hand, words like "consistent," "stable," and "serene" each denote a sense of reliability or calmness, which conflicts with the concept of someone being mercurial. A consistent person maintains the same mood over time; a stable individual's temperaments are steady and predictable; and a serene person exudes tranquility and peace, showing little to no fluctuation in mood. In contrast to these descriptors, "mercurial" accurately highlights the inherent volatility associated with frequent mood shifts.