long face
A facial expression denoting sadness. Jill had such a long face yesterday after she learned that she failed her exam. Hey, kiddo, why the long face? Is something bothering you?
long face
A facial expression showing sadness or disappointment, as in Greg's long face was a clear indication of his feelings. [Late 1700s]
a long face, to wear/draw/pull
To look sad or dissatisfied. A common expression in the nineteenth century, it no doubt came from the elongated look resulting from the mouth being drawn down at the corners and the eyes downcast.