blue(redirected from out of the blue)
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1. 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
a. a sportsman who represents or has represented Oxford or Cambridge University and has the right to wear the university colour (dark blue for Oxford, light blue for Cambridge)
b. the honour of so representing one's university
3. Brit an informal name for Tory
4. any of numerous small blue-winged butterflies of the genera Lampides, Polyommatus, etc.: family Lycaenidae
5. Archery a blue ring on a target, between the red and the black, scoring five points
6. a blue ball in snooker, etc
The hue evoked in an average observer by monochromatic radiation having a wavelength in the approximate range from 455 to 492 nanometers; however, the same sensation can be produced in a variety of other ways.
in American flag, symbolizes justice. [Color Symbolism: Leach, 242; Jobes, 356]