The error is when people say “lip singing”.
It’s a common mistake people make because they associate the actions of singers pretending to sing by moving their lips.
Lip-synching (pronounced ‘sinking’) is short for lip synchronization. It is a technical term for matching lip movements with sung or spoken vocals.
Lip-synching is often warranted, as in the case of music videos produced to simplify sound mixing. However, lip-synching is severely criticized when it occurs during live performances. In these instances, the performer might be viewed as someone without talent and as a fraud.
This video demonstrates how negatively lip-synching is viewed during live performances, and in the case of the band Nirvana, how an artist can rebel against this false practice.