expressionless; blank look; lack of emotion
Describes a face or demeanor showing no emotion; often used with な to modify nouns (無表情な顔) or as a noun (無表情で話す).
彼は無表情な顔で座っていた。
He sat there with an expressionless face.
彼女は無表情でその知らせを聞いた。
She listened to the news without any expression.
He's always expressionless, so I can't tell what he's thinking.
She stared at me with a completely blank face.
I was surprised, but I kept a straight face and continued talking.
He answered the question with no expression on his face.