This is a word which I find rolls of the tongue beautifully (aren’t those the best types?).  The Oxford Dictionary definition is:

“Subject to sudden or unpredictable changes of mood or mind.”

An example of its use would be: ‘her mercurial temperament‘.  I’ve been pondering about whether this word applies to my own temperament, and I suppose it does.  Perhaps that’s simply because I’m female; I can experience as good a mood swing as any.  Both my mother and Olly would testify to that.  Isn’t it strange how they just happen without you even realising or understanding why?

I wouldn’t say the word applied so much to my mind.  I don’t often change my mind unpredictably; I struggle more with making a decision in the first place!

As much as I would love to say that I learnt this word from some educational book, that would be a lie.  I learnt it from Prison Break.  Sigh.