Capriciousness is a term used to describe someone who is unpredictable and prone to sudden changes in mood or behavior. It is related to the terms WHIMSICALITY, WHIMSY, and LIGHTNESS, which all refer to a certain playfulness or lack of seriousness. WHIMSICALITY is the most encompassing of these terms, referring to a state of being that is characterized by a lack of seriousness and a tendency to be unpredictable. WHIMSY is a more specific term, referring to an inclination towards playfulness or humor. LIGHTNESS is also a more specific term, referring to a lack of seriousness or heaviness. All of these terms are related to capriciousness, and together they can be used to describe someone who is unpredictable and prone to sudden changes in mood or behavior.