Definition och Betydelse av "in a world of {one's} own"

What is the origin of the idiom "in a world of one's own" and when to use it?

The idiom "in a world of one's own" originated from the idea of an individual being deeply engrossed in their thoughts, imagination, or daydreams, to the extent that they seem disconnected from their surroundings or the reality experienced by others. The phrase is used to suggest that the person is mentally absorbed in their own inner world, separate from the external environment or social interactions. In other words, this expression conveys a sense of isolation or detachment from the present moment or shared experiences.