Audio latency
Also called audio delay · Bluetooth latency · lip sync
Audio latency is the delay between a sound being produced and you hearing it. Bluetooth adds noticeably more than a wired connection because audio has to be compressed and buffered before it is sent.
In practice
A small delay goes unnoticed in music. It becomes a problem with video, where lips move before the words arrive. Games suffer too when sounds lag behind actions. Bluetooth adds the most latency. Wired headphones and USB audio add very little. Some video players and TVs let you shift audio to compensate.
How to check
Watch a video of someone speaking with Bluetooth headphones and then with wired ones. If the lips match on wired but not on Bluetooth, Bluetooth latency is the cause. Low latency codecs and gaming headsets with their own dongles reduce the delay considerably.