Definitions:
of a colour intermediate between green and violet, as of the sky or sea on a sunny day

(of a person or mood) melancholy, sad, or depressed

(of a film, joke, or story) having sexual or pornographic content

politically conservative

blue colour or pigment

a small butterfly, the male of which is predominantly blue while the female is typically brown.

a person who has represented cambridge university (a cambridge blue) or oxford university (an oxford blue) at a particular sport in a match between the two universities

an argument or fight

a mistake

a nickname for a red-headed person

a supporter of the conservative party.

make or become blue

wash (white clothes) with bluing

squander or recklessly spend (money)