Noun

1. A type of folksong that originated among black americans at the beginning of the 20th century; has a melancholy sound from repeated use of blue notes
2. A state of depression
3. Blue color or pigment; resembling the color of the clear sky in the daytime
4. Blue clothing
5. Any organization or party whose uniforms or badges are blue
6. The sky as viewed during daylight
7. Used to whiten laundry or hair or give it a bluish tinge
8. The sodium salt of amobarbital that is used as a barbiturate; used as a sedative and a hypnotic
9. Any of numerous small butterflies of the family lycaenidae

Verb

1. Turn blue