whimsical

Concise Oxford English Dictionary © 2008 Oxford University Press:
whimsical/ˈwɪmzɪkl/

▶adjective

• 1 playfully quaint or fanciful, especially in an appealing and amusing way.

• 2 acting or behaving in a capricious manner.

– derivatives
whimsicality noun,
whimsically adverb.