blues

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun plural A state of depression or melancholy. Often used with the.
• noun plural A style of music that evolved from southern African-American secular songs and is usually distinguished by a strong 4/4 rhythm, flatted thirds and sevenths, a 12-bar structure, and lyrics in a three-line stanza in which the second line repeats the first.

from the GNU version of the Collaborative International Dictionary of English.

• noun a type of folk song that originated among Black Americans at the beginning of the 20th century; has a melancholoy sound from repeated used of blue notes.
• noun a state of depression.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Plural form of blue.
• noun informal A feeling of sadness or depression.
• noun singular or plural, informal One's particular life experience, particularly including the hardships one has faced.
• noun A musical form, African-American in origin, generally featuring an eight-bar or twelve-bar structure and using the blues scale.
• noun music, always singular A musical composition following blues forms.
• noun A uniform made principally of a blue fabric.
• noun sports Any of a number of sports teams which wear blue kit.
• verb Third-person singular simple present indicative form of blue.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a state of depression
• noun 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