whimsey

noun

1
the trait of acting unpredictably and more from whim or caprice than from reason or judgment
I despair at the flightiness and whimsicality of my memory
2
an odd or fanciful or capricious idea
the theatrical notion of disguise is associated with disaster in his stories
he had a whimsy about flying to the moon

Also useful for “whimsey”:Unscrambler— Rearrange the letters in “whimsey”