lip-sync

or lip·synch, lip·sync

[lip-singk]Movies, Television.

verb (used with or without object)

to synchronize (recorded sound) with lip movements, as of an actor in a film.
to match lip movements with (recorded speech or singing): She did a clumsy job of lip-syncing her big song.

noun

the technical process by which this is done.
the simultaneous recording of voice and picture, especially the synchronization of lip movements with recorded sound.

Origin of lip-sync

First recorded in 1960–65
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for lip-synch

lip-synch

lip-sync

verb

to mouth (prerecorded words) on television or film
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012