n.combining audio and video recording in such a way that the sound is perfectly synchronized with the action that produced it; especially synchronizing the movements of a speaker's lips with the sound of his speech
v.move the lips in synchronization (with recorded speech or song)
同义词：lip-sync
英汉双解大词典
lip-synch(alsolip-sync)
1.
V-T/V-I（及物动词/不及物动词）
If you lip-synch, you pretend to be singing or playing an instrument, although the music is in fact coming from a CD or cassette. 假唱 [英国英语]