Wiktionary
n. The elapsed time between two events
Usage examples of "lagtime".
You have maybe fifteen minutes lagtime before it knows what you are (your noise getting to its receptors at lightspeed).
And fifteen minutes lagtime for its beams to reach where it predicts you will be fifteen minutes later (or less if you're going toward it) -- if it fired at once.
When you arrive at a star, you come in at the stellar zenith pole as agreed by navigational law, slow down at once, Your arrival has been reported by a jump range buoy which is a robot station which has three functions: first, it gives you a current updated computer image of the estimated positions of every object in the solar system, cutting down on the lagtime problems.
The lagtime shortens from an hour to half and hour to five minutes to no appreciable lag as you get to the station and begin docking.
There was lagtime to contend with on that request, nothing to do but wait.
How long would it take you, not counting ninety-six minutes of lagtime, to get Tweed on the radio, talk to him and get his answer?