- caprice, impulse, whim - a sudden desire; "he bought it on an impulse"
--1 is a kind of desire
- notion, whim, whimsy, whimsey - 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"; "whimsy can be humorous to someone with time to enjoy it"
--2 is a kind of idea, thought