in a world of (one's) own

in a world of (one's) own

Consumed by one's thoughts, imagination, etc., to such a degree that one is unaware of or insensitive to one's surroundings and/or the outside world in general. 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
Farlex Dictionary of Idioms.

*in a world of one's own

Fig. aloof; detached; self-centered. (*Typically: be ~; get [into] ~; live ~.) John lives in a world of his own. He has very few friends. Mary walks around in a world of her own, but she's very intelligent.
See also: of, own, world
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • be in a world of (one's) own
  • be, live, etc. in a world of your own
  • at the back of (one's) mind
  • at the back of your mind
  • at (one's) doorstep
  • at doorstep
  • be written all over (one's) face
  • be written all over somebody's face
  • be written all over your face
  • a change of scenery