expression, ichidan verb
open one's eyes slightly; crack one's eyes open
Describes the action of opening the eyes just a little, often when waking up, peeking, or trying to see without being noticed.
朝、薄目を開けて時計を見た。
In the morning, I cracked my eyes open and looked at the clock.
彼は薄目を開けて、誰が来た
He opened his eyes slightly to check who had come.