noun1. any of a group of colours, such as that of a clear unclouded sky, that have wavelengths in the range 490–445 nanometres. Blue is the complementary colour of yellow and with red and green forms a set of primary colours
▶ Related adjective:
cyanic 2. a dye or pigment of any of these colours
3. blue cloth or clothing
dressed in blue
4. a. a person who represents or has represented Oxford or Cambridge University in a sport and has the right to wear the university colour (dark bluefor Oxford, light blue for Cambridge)
an Oxford blue
b. the honour of so representing one's university
5. British an informal name for Tory
6. any of numerous small blue-winged butterflies of the genera Lampides, Polyommatus, etc: family Lycaenidae
7. archaic short for bluestocking
8. slang a police officer
9. archery a blue ring on a target, between the red and the black, scoring five points
10. a blue ball in snooker, etc
11. another name for blueing
12. Australian and New Zealand slang an argument or fight
he had a blue with a taxi driver
13. Also: bluey Australian and New Zealand slang a court summons, esp for a traffic offence
14. Australian and New Zealand informal a mistake; error
15. out of the blue
16. into the blue
adjectiveWord forms: bluer or bluest18. (of the flesh) having a purple tinge, as from cold or contusion
19. depressed, moody, or unhappy
20. dismal or depressing
a blue day
21. indecent, titillating, or pornographic
blue films
22. bluish in colour or having parts or marks that are bluish
a blue fox
a blue whale
23. rare aristocratic; noble; patrician
a blue family
blue blood
24. US relating to, supporting, or representing the Democratic Party
Compare red1 (sense 18) verbWord forms: blues, blueing, bluing or blued25. to make, dye, or become blue
26. (transitive) to treat (laundry) with blueing
27. (transitive) slang to spend extravagantly or wastefully; squander
Word origin
C13: from Old French
bleu, of Germanic origin; compare Old Norse
blār, Old High German
blāo, Middle Dutch
blā; related to Latin
flāvus yellow