“Dream when you’re feeling blue”, sang Ray Charles. Shakespeare’s Cleopatra talked famously of her salad days when she was “green in judgement”; the Everley Brothers sang of all their friends being “just about green with envy”. Depeche Mode wrote a whole song about a black day, and Cyndi Lauper saw someone’s “true colors shining through”. The poetic use of color in a metaphorical rather than a literal sense — to describe everything from moods to bank-balances, political affiliations to social classes — dates back centuries and permeates most modern languages. Colors themselves have metaphorical meanings that are universal across cultures and languages. Here’s a summary of their figurative meanings, which are often evoked as keenly and understood as universally as the hues they describe literally.

Blue: 

Blue usually has a sense of melancholy, depression or despondency (and is connected with the music genre “the blues”, with the same feeling of sadness). According to the Online Etymology Dictionary, blue meaning “depression, low spirits” goes back to 1741, from the adjectival blue “low-spirited,” late 14c. The Oxford English Dictionary offers these figurative definitions of the adjective: (Of a person, the heart, etc.) “depressed, low-spirited, sad, sorrowful; dismayed, downcast”; (of a state or feeling) “miserable, melancholy, dejected.” In early use it was often found in to look blue; it’s now frequently used in the context of feeling blue (originally an American phrase).

Blue blood: “A literal translation of the Spanish ‘sangre azul’, attributed to some of the oldest and proudest families of Castile, who claimed never to have intermarried with Moors, Jews, or other races. The expression probably originated in the blueness of the veins of people of fair complexion as compared with those of dark skin.” (from PhraseFinder)

Blue phrases: out of the blue (unanticipated); to blue-pencil (edit); blue collar (working-class); a bolt from the blue (sudden, unexpected event); look/feel blue (sad); until you’re blue in the face (useless, futile); once in a blue moon (rarely); men/boys in blue (policemen); blue comedy/working blue (profane, indecent, risque); talk up a blue streak (rapidly and excitedly); blue-blooded (aristocratic); into the wide (or wild) blue yonder (referring to sky); blue on blue (members of same force firing on one another)

Green

The color used to describe the pallor of someone feeling nauseous, and the bile of extreme envy causing nausea. In nature, green represents youth (as in green wood, or unripe fruits) and hence its association with inexperience or naivety. Its positive ecological and environmental associations are more literal, given the preponderance of the color green in nature.

Green phrases: to be green (naive); green with envy; give/get the green light (permission or authority); grass is always greener on the other side; green belt (area of land around a city); green thumb or green fingers (talent for growing plants); green around the gills (sickly-looking); green on blue (phrase used to describe attacks on NATO forces by members of the Afghan security forces); green shoots (signs of economic recovery)

Red

Red is the color of fire and blood, and thus symbolizes emotional extremes caused by spilled or rising blood — indicating everything from guilt (“caught red-handed”) to anger, embarrassment, shame, and physical exertion. With its high visibility it is also the color of authority, importance, royalty and bureaucracy, as well as danger. In financial terms, being “in the red” means you don’t have enough income to meet operating expenses; or, more simply put, you owe someone money.

Red phrases: to be shown the red card (to a football player being sent off the field); to be in/out of the red (in debt); catch someone red-handed (in the act);  to see red (be angry); red tape (bureaucracy); to see the red light (stop); paint the town red (go out and enjoy oneself); roll out the red carpet (give guest special treatment); redneck (working-class reactionary white person from rural area); a red herring (a clue deliberately misleading); red-letter day (a day that is pleasantly noteworthy or memorable)

Black

Representing extreme metaphorical darkness, black is the color of evil and, by extension, of the Devil and the supernatural in general. It is the color of mourning, as well as a mark of misdemeanor or bad behavior.

Black phrases: black and white (very clear; cf. grey below); to black out (lose consciousness); black sheep (odd one out); in the black (profitable); black market (illegal traffic or trade); in someone’s black books (in disfavor); the pot calling the kettle black (a hypocritical accusation); to blackball (reject by secret ballot); (to) blackmail (demanding money in return for not revealing compromising or injurious information); blacklist (list of people viewed with suspicion or disapproval)