Blue has 22 different meanings across 4 categories:
Noun · Verb · Adjective · Proper Noun
the sky as viewed during daylight
"he shot an arrow into the blue"
the sodium salt of amobarbital that is used as a barbiturate; used as a sedative and a hypnotic
"After taking too much blue, he fell into an unshakeable sleep that lasted until noon."
any of numerous small butterflies of the family Lycaenidae
"We spotted a cluster of blue fluttering near the clover patch earlier today."
The colour of the clear sky or the deep sea, between green and violet in the visible spectrum, and one of the primary additive colours for transmitted light; the colour obtained by subtracting red and green from white light using magenta and cyan filters; or any colour resembling this.
"The blue from his university jacket was worn but clearly showed he had earned a place as an undergraduate at either Oxford or Cambridge."
A letterman at Oxford or Cambridge.
In plain English: Blue is a color that looks like the sky on a clear day or deep ocean water.
"She wore a blue dress to the party."
Usage: Use "blue" as a noun to refer specifically to a student wearing the blue blazer of Oxford or Cambridge University's undergraduate societies. This usage is rare and largely historical, so it should be avoided in modern general conversation where the color is almost always an adjective.
To make or become blue.
"After winning the lottery, he decided to go on a world tour and blue every last cent he had saved."
To spend (money) extravagantly; to blow.
In plain English: To blue something means to color it with blue paint or dye.
"He decided to blue his jeans before hanging them up."
Usage: Use "blue" as a verb only in informal contexts to mean spending money recklessly or blowing it on something unnecessary. This usage is specific to colloquial speech and should not be confused with the color or the musical note.
used to signify the Union forces in the American Civil War (who wore blue uniforms)
"a ragged blue line"
filled with melancholy and despondency
"gloomy at the thought of what he had to face"
"gloomy predictions"
"a gloomy silence"
"took a grim view of the economy"
"the darkening mood"
"lonely and blue in a strange city"
"depressed by the loss of his job"
"a dispirited and resigned expression on her face"
"downcast after his defeat"
"feeling discouraged and downhearted"
characterized by profanity or cursing
"foul-mouthed and blasphemous"
"blue language"
"profane words"
belonging to or characteristic of the nobility or aristocracy
"an aristocratic family"
"aristocratic Bostonians"
"aristocratic government"
"a blue family"
"blue blood"
"the blue-blooded aristocracy"
"of gentle blood"
"patrician landholders of the American South"
"aristocratic bearing"
"aristocratic features"
"patrician tastes"
morally rigorous and strict
"puritanic distaste for alcohol"
"she was anything but puritanical in her behavior"
"blue laws"
Having blue as its color.
"The sky turned a deep blue just before sunset."
In plain English: Blue is the color of the sky on a clear day and the ocean when you look at it from far away.
"The sky turned a deep blue color just before sunset."
Usage: Use "blue" to describe objects that reflect or emit light with a wavelength between violet and green, such as the sky or jeans. Avoid using it metaphorically for sadness unless you are specifically referring to an emotional state rather than a physical appearance.
A surname, from German. An anglicization of German Blau.
"My neighbor Mr. Blue invited us over for dinner, and we realized he wasn't wearing blue clothes at all."
The word "blue" traveled into English from Old French and Middle French, where it originally meant the color we know today. Its ultimate roots lie in a Proto-Indo-European term that actually referred to yellow or blond hair before shifting in meaning over time.