Jazz-funk is a sub-genre of jazz music characterized by a strong back beat (groove), electrified sounds, and often, the presence of the first electronic analog synthesizers. The integration of funk, soul, and R&B music and styles into jazz resulted in the creation of a genre whose spectrum is indeed quite wide and ranges from strong jazz improvisation to soul, funk or disco with jazz arrangements, jazz riffs, and jazz solos, and sometimes soul vocals.

source: wikipedia