What does jetlagged mean?

Answer 1

Jet-lag is the difficulty adapting to changes in time zones after a flight.
A temporary disruption of the body's biological clock experienced by persons who travel across several time zones by airplane.

Jet lag occurs because the body of a traveler cannot immediately adjust to the time in a different zone. It make's you feel wide awake when you should be sleeping or very sleepy in the middle of the day. There are two interesting claims I've heard about jet lag; firstly the human body clock operates on a 23 hour day - the Earth has slowed down over time. This effectively means that we're all permanently jet-lagged. Secondly, birds don't get jet-lag when they migrate. This is because they don't fly east/west but north/south so don't change time zones. == == LAG is a generalistion for the time taken for a response from Computer 2 when Computer 1 has requested a resource. This is most commonly used in "online gaming" where LAG can be refered to as a physical slowdown as you (computer 1) is waiting for an update from the Server (computer 2). LAG is a term for any delay in this operation, usually measured in milliseconds. GET LAG is a delay in data coming from the Server (computer 2) SEND LAG is a delay in the Client (computer 1) Sending the request for data.

Answer 2

It means after a long flight you are tired because of time zone changes.