Long face is an idiomatic expression used to describe someone who appears sad or dejected. There are several synonyms for long face that can be used interchangeably, such as a gloomy expression, dejected look, sorrowful countenance, and mournful appearance. These synonyms can be used to describe someone who is feeling down and has a sad expression. Whether it is a result of personal problems or due to a tough situation, these synonyms can come in handy when describing someone who appears to be feeling sadness or melancholy. It is important to use these synonyms sensitively, and always considerate of the other person's feelings.