Whimsical
Whimsical (adj) /ˈwɪm.zɪ.kəl/
slightly unusual in a humorous and amusing way – odd – witty – bizarre – peculiar – fanciful – imaginative – erratic:
His whimsical sense of wry humor in the face of life vicissitudes had literally stunned his acquaintances.
Antonyms: practical, serious, dependable
Noun: whimsicalness
Noun: whimsicality
Adverb: whimsically