long face
n.
A discontented or sullen facial expression.

[TahlilGaran] American Dictionary ▲

long face
if you have a long face, you look sad.
'Why've you got such a long face?' 'My boyfriend doesn't want to see me any more.'

[TahlilGaran] English Idioms Dictionary ▲

long face
a sad look, a disappointed look
He had a long face when he came into work this morning. Something must have happened to him.

[TahlilGaran] English Idioms Dictionary ▲

long face
n. A sad look; disappointed look.
He told the story with a long face.
■ Often used in the phrase "pull a long face".
Don't pull a long face when I tell you to go to bed.

[TahlilGaran] English Idioms Dictionary ▲