melancholy melancholy /ˈmɛlənˌkɑːli/

adjective

1. () Characterized by, causing or expressing sadness  ( melancholic , melancholy )
   characterized by, causing or expressing sadness
    Growing more melancholy every hour
   growing more melancholy every hour
    Her melancholic smile
   her melancholic smile
    We acquainted him with the melancholy truth
   we acquainted him with the melancholy truth
   
2. Grave or even gloomy in character  ( melancholy , somber [American] , sombre [Canadian, British] )
   grave or even gloomy in character
    Solemn and mournful music
   solemn and mournful music
    A suit of somber black
   a suit of somber black
    A somber mood
   a somber mood
   

noun

1. () A feeling of thoughtful sadness  ( melancholy )
   a feeling of thoughtful sadness
     The haunting melody filled the room with a sense of melancholy and nostalgia.
   The haunting melody filled the room with a sense of melancholy and nostalgia.
   
2. [Archaic] A humor that was once believed to be secreted by the kidneys or spleen and to cause sadness and melancholy  ( black bile , melancholy [Archaic] )
   a humor that was once believed to be secreted by the kidneys or spleen and to cause sadness and melancholy
   
3. A constitutional tendency to be gloomy and depressed  ( melancholy )
   a constitutional tendency to be gloomy and depressed