lose oneself in

lose in

1. To misplace or mislay someone or something in some particular location. In this usage, a noun or pronoun is used between "lose" and "in." I lost my phone in the airport somewhere. My parents actually lost me in a supermarket when I was two.
2. To become so mentally involved in or preoccupied by something as to be oblivious to everything and everyone else around oneself. In this usage, a reflexive pronoun is used between "lose" and "in." I love losing myself in a good book. He had lost himself in the stunning scenery, so he hadn't heard what I said.
See also: lose
Farlex Dictionary of Idioms.

lose oneself in someone or something

to be thoroughly absorbed in someone or something; to become engrossed in someone or something. Frank loses himself in his children when he is at home. When I lose myself in my work, time just rushes by.
See also: lose
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

lose oneself in

Become deeply absorbed or involved in, as in Doctors are notorious for losing themselves in their work. This expression alludes to becoming so absorbed as to forget oneself. [c. 1600]
See also: lose
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • lose in
  • lost in
  • orient
  • orient to
  • orient to (something)
  • spiff up
  • spiffed up
  • angle
  • angling
  • identify with