melancholy
noun
a feeling of thoughtful sadness
a constitutional tendency to be gloomy and depressed
a humor that was once believed to be secreted by the kidneys or spleen and to cause sadness and melancholy
Synonymsblack bile
adjective
characterized by or causing or expressing sadness
“growing more melancholy every hour”
“her melancholic smile”
Synonymsmelancholicgrave or even gloomy in character
“solemn and mournful music”
“a suit of somber black”
Source: WordNet 3.1, Princeton University