in a world of your own

US /ɪn ə wɜrld əv jʊər oʊn/
UK /ɪn ə wɜrld əv jʊər oʊn/
"in a world of your own" picture
1.

自分の世界にいる, 空想にふける

living in your own thoughts and imagination, often unaware of what is happening around you

:
She's often in a world of her own, dreaming about her next novel.
彼女はよく自分の世界にいて、次の小説について夢見ている。
He was so deep in a world of his own that he didn't hear me call his name.
彼は自分の世界に深く入り込んでいて、私が名前を呼ぶのが聞こえなかった。