English Reference

Word

blue

US/ˈbɫu/

UK/blˈuː/

Definitions

01the colour

A1 · Beginner Uncountable noun

n. the colour of the clear sky or the sea.

n. the colour between green and violet in the visible spectrum; one of the primary additive colours.

“The artist used a bright blue for the sky in her painting.”

“The deep blue of the Mediterranean was captured perfectly in the photographer's latest series of coastal landscapes.”

Synonyms

02colour description

A1 · Beginner

adj. having the colour of the sky or sea.

adj. possessing a blue hue or tint.

“He wore a blue shirt that matched his eyes.”

“The architect specified blue tinted glass for the skyscraper to reflect the surrounding atmosphere.”

03feeling sad

B1 · Intermediate Informal

adj. feeling sad, unhappy, or without hope.

adj. experiencing low spirits, melancholy, or mild depression.

“I was feeling a bit blue after my best friend moved away.”

“Despite the festive atmosphere, he couldn't help feeling blue on the anniversary of his father's passing.”

Antonyms

04political affiliation

B2 · Upper Intermediate Politics

adj. related to a specific political party, like the Democrats in the US or Conservatives in the UK.

adj. pertaining to a political party represented by the colour blue; usage varies by country.

“California is known as a blue state in American presidential elections.”

“The candidate focused her campaign efforts on traditionally blue districts where voter turnout was expected to be high.”

Antonyms

red

05obscene or risqué

C1 · Advanced Informal

adj. containing jokes or stories about sex that some people might find offensive.

adj. referring to content that is risqué, indecent, or contains profane language.

“The comedian was famous for his blue jokes that were only for adults.”

“The film was edited for television to remove the bluer segments of the dialogue that were deemed inappropriate for a general audience.”

Synonyms

risquéobscenevulgar

Antonyms

06the sky or sea

B2 · Upper Intermediate Uncountable noun Literary

n. a poetic way to talk about the sky or the ocean.

n. a metonymic reference to the clear sky or the deep ocean.

“The eagle soared high up into the wide blue.”

“The sailors stared out into the endless blue, searching for any sign of land after weeks at sea.”

Synonyms

07an argument or fight

C2 · Proficiency Countable noun Dialect · Informal

n. a fight, a loud argument, or a mistake.

n. a physical brawl, a heated verbal argument, or a significant blunder.

“The two players got into a blue on the field during the game.”

“A massive blue erupted outside the pub after the local team lost the grand final.”

Usage

Primarily used in Australian and New Zealand English.

Teaching tip

Learners should be aware this is highly regional; in most other dialects, 'blue' never means a fight.

Synonyms

08to turn blue

C1 · Advanced Technical

v. to make something blue or to become blue.

v. to cause to become blue; to treat a surface so it takes on a blue tint.

“The cold weather blued his lips as he waited for the bus.”

“The craftsman carefully blued the steel barrels of the antique firearm to protect them from corrosion.”

Collocations

Common phrases and expressions where native English speakers use the word “blue” in context.

01. blue whales 02. blue stars

Real-World Examples

“The blue of the sky is the product of Rayleigh scattering, which affects light more at the blue end of the spectrum.”
The Guardian 29 Jan 2026
“The colour of the iconic dye is akin to a clear blue sky or the turquoise of the nearby Caribbean Sea.”
Al Jazeera 1 Dec 2024
“The blue of the sea and sky is as hard to grasp as the concept itself.”
The Globe and Mail 23 Dec 2021

Etymology

From the German surname, Americanized from Blau or its French cognate Bleu.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Word family

ADJECTIVE

Related words

Idioms

Domains

AstronomyPolitics

This entry

Exam level
CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.A1 MoversIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.2.0–3.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 1.0–1.50–23TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.120–224
Frequency
Very common
Level
A1 · BeginnerOxford
Updated

QR code

englishreference.com/q/blue

English Reference