Be in a world of one's own - Idioms by The Free Dictionary
be in a world of (one's) own (redirected from 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.
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.