Of a color 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 movie, joke, or story) with sexual or pornographic content. Rigidly religious or moralistic; puritanical. Blue color or pigment. A blue thing, in particular. A small butterfly, the male of which is predominantly blue while the female is typically brown. Make or become blue. Wash (white clothes) with bluing.