Jazz is a musical genre, a style in itself, an action, adjective, and foundation for a certain social group.
1. A music that originated in America, and credited to slaves who brought it over from West Africa. Has rhythmic foundations from the beats and syncopations from Africa. Has instrumental timbres from Spanish and European influences, as a result of the Spanish-American war and the diversity in New Orleans. Also has roots from ragtime piano, and eventually later on swing, blues, and bebop. Usually uses improvisation, but not always.
2. A verb similar to "swing". To give something a looser, more free-flowing, hipper feel. Can be done to a simple rhythm, or even things outside of music as in a "jazzed up place".
3. Often a thing that certain musical purists use to defend themselves as being the only decent kind of music left these days. Results in a kind of jazz elitism, where a jazz enthusiast believes he or she is better because he or she listens to the only kind of music that is still authentic and good.
1. Some jazz musicians include Duke Ellington, John Coltrane, Vince Guaraldi, Diana Krall, etc etc.
2. This beat is too boring, we got to jazz it up a bit.
3. I don't listen to your repulsive rap, rock, or other mainstream pop. I'm close-minded and will forever be in my own little jazz bubble, which of course is the greatest gift America has for the world.