1.Definition: belonging to or characteristic of the nobility or aristocracy
"A blue family", "Blue blood", "The blue-blooded aristocracy"
2.Definition: causing dejection
"A blue day"
3.Definition: characterized by profanity or cursing
4.Definition: filled with melancholy and despondency
"Lonely and blue in a strange city"
6.Definition: of the color intermediate between green and violet; having a color similar to that of a clear unclouded sky
"October's bright blue weather", "A blue flame", "Blue haze of tobacco smoke"
7.Definition: suggestive of sexual impropriety
"A blue movie", "Blue jokes"
8.Definition: used to signify the Union forces in the American Civil War (who wore blue uniforms)
"A ragged blue line"