Jazz (definition): A type of music of black American origin which emerged at the beginning of the 20th century, characterized by improvisation, syncopation, and usually a regular or forceful rhythm. Brass and woodwind instruments and piano are particularly associated with jazz, although guitar and occasionally violin are also used; styles include Dixieland, swing, bebop, and free jazz.
Other Uses of the Word ‘Jazz’
U.S. slang. Energy, excitement, ‘pep’; restlessness; animation, excitability. Now rare. In early use frequently in contexts relating to baseball; used attributes to describe a deceptively difficult and fast throw.
colloq. (chiefly U.S.):
a. Unnecessary, misleading, or excessive talk; nonsense, rubbish.
b. Something that one regards as hard to describe or understand; (more generally) ‘stuff’, ‘things’. Chiefly depreciative.
c. and all that jazz: and all that sort of thing; and stuff like that; and so on; et cetera.
Music:
a. A type of popular music originating (esp. in ragtime and blues) among African Americans in the southern United States, typically performed by ensembles and broadly characterized by regular forceful rhythms, syncopated phrasing, modifications to traditional instrumental tone and pitch (such as the use of blue notes), and improvisatory soloing.
b. (a) A piece of jazz music (now rare); (b) spec. a passage of improvised music in a jazz performance (rare).
c. Any of various styles of dance performed to or associated with jazz music; spec. (a) (freq. with the) a ragtime dance (now rare); (b) a dance form having its roots in popular and theatrical dance and characterized especially by athletic movements and an emphasis on improvisation.
U.S. slang. Sexual intercourse; an instance of this
adj. (chiefly attrib.)
a. Suggestive of jazz (in various senses), jazzy; lively; sophisticated; unconventional.
b. Of patterns, fabric, clothing, etc.: having a bold or fantastic design; marked by vivid or riotous colouring.
Sources: http://www.oxforddictionaries.com/definition/english/jazz?q=jazz , http://www.oed.com/viewdictionaryentry/Entry/100938