Short for the word New Jack Swing, used för the music genre that had its biggest years in the late 80's until the mid 90's. It is a hybrid of R&B and sounds like hip hop with a more "swinging" sound on the beats, with the r&b style of singing.
Teddy Riley is said to be the father of New Jack Swing, also Tony Toni Toné, Johnny Gill, Gerald Levert, Bobby Brown, Blackstreet, New Edition and Guy were big names in the New Jack era.
The movie New Jack City (1991) also contains a lot of New Jack Swing music.
"Don't believe a thing about the New Jack Swing!"