As a verb,
fall behind in movement, progress, or development; not keep pace with another or others.
As a noun in physics,
a retardation in an electric current or movement.
Commonly used in 2 scenarios
When traveling to another region with a different time zone and you need to adjust your sleep cycle to it is know as "Jet Lag"
When playing an online game and having high latency with the online service causing your game to partialy freeze or seems to jump in time
"they stopped to wait for one of the children who was lagging behind"
"I have a lot of lag, i cant play like this"
Malicious compliance (also known as malicious obedience) is the behavior of strictly following the orders of a superior despite knowing that compliance with the orders will have an unintended or negative result. It usually implies following an order in such a way that ignores or otherwise undermines the order's intent but follows it to the letter.
Malicious compliance example
PE teacher: You will do laps until your feet are bleading
PE teacher: Why didn't you stop when your shoes tore apart? your feet are bleeding