be in a world of (one's) own

be in a world of (one's) own

To be unaware of or insensitive to the outside world. It's no use trying to talk to Helen about something like this—she's always in a world of her own.

See also: of, own, world

be, live, etc. in a world of your ˈown

seem not to be aware of things happening around you; be a person who has ideas that other people think are strange: I’m not surprised he didn’t know about it — he lives in a world of his own, that boy.

See also: of, own, world