Playing any groove twice as fast as its regular tempo, while the measures of music continue as normal. Often confused with Half-time. To achieve this, the back-beat is played on the & or AND of the beat, rather than the normal fashion ... playing on beats 2 and 4 as in 4/4 time. There is also a music notation for cut-time where the music is written normally, but you are instructed to play it twice as fast ... which is what cut-time means.

This terms is used in relation to the pulse of the music, which, 99% of the time, is the quarter-note.