The word disappointment refers to a feeling of being let down, or to something that produces that feeling by failing to fulfill expectations or wishes. The noun chagrin is more pointed: this word refers to a feeling of vexation or irritation marked by disappointment or humiliation—or both!

The word changeable can mean simply capable of being changed or, more often, liable or likely to change. Mercurial is closer to the latter; it emphasizes volatility, fickleness, and unpredictability, and is commonly used to describe person’s temperament. But even the meaning of mercurial shifts from time to time; this hard-to-pin-down adjective can also take a more positive turn to mean animated, lively, or quick-witted.

A conclusion is a final part or summing up of something. A denouement is a final resolution or tidying up of the intricacies of a plot, as in a drama or novel, often a tragedy. The literary application of denouement sets it apart from the much more general term conclusion. However, denouement is also used to refer to outcomes or resolutions of a series of occurrences that may read like a novel or drama, but take place—however regrettably—in real life.