melancholic adj.

c. 1300, melancolie, malencolie, "mental disorder characterized by sullenness, gloom, irritability, and propensity to causeless and violent anger," from Old French melancolie "black bile; ill disposition, anger, annoyance" (13c.), from Late Latin melancholia, from Greek melankholia "sadness," literally (excess of) "black bile," from melas (genitive melanos) "black" (see melano-) + khole "bile" (see cholera).

Old medicine attributed mental depression to unnatural or excess "black bile," a secretion of the spleen and one of the body's four "humors," which help form and nourish the body unless altered or present in excessive amounts. The word also was used in Middle English for "sorrow, gloom" (brought on by love, disappointment, etc.), by mid-14c. As belief in the old physiology of humors faded out in the 18c. the word remained with a sense of "a gloomy state of mind," particularly when habitual or prolonged.

The Latin word also is the source of Spanish melancolia, Italian melancolia, German Melancholie, Danish melankoli, etc. Old French variant malencolie (also in Middle English) is by false association with mal "sickness."

When I go musing all alone,

Thinking of divers things fore-known,

When I build castles in the air,

Void of sorrow and void of fear,

Pleasing myself with phantasms sweet,

Methinks the time runs very fleet.

   All my joys to this are folly,

   Naught so sweet as melancholy.

When I lie waking all alone,

Recounting what I have ill done,

My thoughts on me then tyrannise,

Fear and sorrow me surprise,

Whether I tarry still or go,

Methinks the time moves very slow.

   All my griefs to this are jolly,

   Naught so sad as melancholy.

[Robert Burton, from "Anatomy of Melancholy," 17c.]

Middle English -ik, -ick, word-forming element making adjectives, "having to do with, having the nature of, being, made of, caused by, similar to," from French -ique and directly from Latin -icus or from cognate Greek -ikos "in the manner of; pertaining to." From PIE adjective suffix *-(i)ko, which also yielded Slavic -isku, adjectival suffix indicating origin, the source of the -sky (Russian -skii) in many surnames. In chemistry, indicating a higher valence than names in -ous (first in benzoic, 1791).

In Middle English and after often spelled -ick, -ike, -ique. Variant forms in -ick (critick, ethick) were common in early Modern English and survived in English dictionaries into early 19c. This spelling was supported by Johnson but opposed by Webster, who prevailed.

Proto-Indo-European root meaning "to shine;" it forms words for "gold" (the "bright" metal), words denoting colors, especially "yellow" and "green," also "bile, gall," for its color, and a large group of Germanic gl- words having to do with shining and glittering and, perhaps, sliding. Buck says the interchange of words for yellow and green is "perhaps because they were applied to vegetation like grass, cereals, etc., which changed from green to yellow."

It forms all or part of: arsenic; Chloe; chloral; chloride; chlorinate; chlorine; chloro-; chloroform; chlorophyll; chloroplast; cholecyst; choler; cholera; choleric; cholesterol; cholinergic; Cloris; gall (n.1) "bile, liver secretion;" gild; glad; glance; glare; glass; glaze; glazier; gleam; glee; glib; glide; glimmer; glimpse; glint; glissade; glisten; glister; glitch; glitter; glitzy; gloaming; gloat; gloss (n.1) "glistening smoothness, luster;" glow; glower; gold; guilder; jaundice; melancholic; melancholy; yellow; zloty.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit harih "yellow, tawny yellow," hiranyam "gold;" Avestan zari "yellow;" Old Persian daraniya-, Avestan zaranya- "gold;"  Greek khlōros "greenish-yellow color,"  kholos "bile, gall, wrath;"  Latin helvus "yellowish, bay," Gallo-Latin gilvus "light bay;" Lithuanian geltonas "yellow;" Old Church Slavonic zlutu, Polish żółty, Russian zeltyj "yellow;" Latin galbus "greenish-yellow," fellis "bile, gall;" Lithuanian žalias "green," želvas "greenish," tulžis "bile;" Old Church Slavonic zelenu, Polish zielony, Russian zelenyj "green;" Old Irish glass, Welsh and Breton glas "green," also "gray, blue;" Old English galla "gall, bile," geolu, geolwe, German gelb, Old Norse gulr "yellow;" Old Church Slavonic zlato, Russian zoloto, Old English gold, Gothic gulþ "gold;" Old English glæs "glass; a glass vessel."