From Latin melancholicus, from Ancient Greek μελαγχολικός, from μελαγχολία ("melancholy").

melancholic

1. Filled with or affected by melancholy—great sadness or depression, especially of a thoughtful or introspective nature.
   • 1718, Mat[thew] Prior, “Alma: Or, The Progress of the Mind”, in Poems on Several Occasions, London: […] Jacob Tonson […], and John Barber […], →OCLC ↗:

     Just as the melancholic eye / Sees fleets and armies in the sky.

2. (dated) Pertaining to black bile (melancholy).
3. (classical temperament) Pertaining to the melancholic temperament or its associated personality traits.

• French: mélancolique
• German: melancholisch, schwermütig
• Italian: malinconico, melancolico
• Portuguese: melancólico
• Russian: меланхоли́ческий
• Spanish: melancólico

melancholic (plural melancholics)

1. A person who is habitually melancholy.

• Russian: меланхо́лик