Capricious
Part of speech: adjective
Definition: Impulsive and unpredictable; determined by chance, impulse, or whim
Example sentence: Makeup is only fun if it's occasional and capricious - just like it's a treat to have an empty day ahead, but it wouldn't be if you were doing 20 years in Parkhurst.
Whimsical
Part of speech: adjective
Definition: Given to whimsy; capricious; odd; peculiar; playful; light-hearted or amusing.
Example sentence: When you're young, you're always wondering when you're actually going to feel like a grownup. And I think you probably fear it, in a sense, too. There's a danger to feeling like an adult... like this whimsical kid in you is going to die or something. And then all of a sudden, one day you kind of feel like an adult and it's really nice.