Lip synching
practice used in the music industry consisting in moving the lips silently in synchronization with a pre-recorded audio track, thus giving the illusion of singing or speaking live
Lip synching is when a person moves his or her lips at the same time as a recorded sound or with another person. Some artists lip sync a live performance because they are not as confident and want to avoid hitting possible bad notes.
Lip syncing by singers can be controversial to fans attending concert performances who expect to view a live performance.
The word synch is short for synchronize, meaning to do something at the same time.