post-synchronization
/ˌpəʊs(t)ˌsɪŋkrənʌɪˈzeɪʃn/Film and Video Recording
noun
The action or process of post-synchronizing a film, video, etc.; the addition of a sound recording to the corresponding images of a film or video after shooting.
Origin
1930s; earliest use found in Adrian Bunel (1892–1958). From post- + synchronization, after post-synchronize.