expression
Attaches to the negative stem (nai-stem) of verbs; for サ変 verbs, use せずに. Expresses that an action is not performed while another action occurs. Often interchangeable with ないで, but ずに is slightly more formal or literary.
See also: ないで
朝ごはんを食べずに学校へ行った。
I went to school without eating breakfast.
彼は何も言わずに部屋を出て行った。
He left the room without saying anything.
勉強せずに試験を受けるのは無理だ。
It's impossible to take the exam without studying.