stay time

noun3

1. •
   Of the usage of a rocket engine, the mean value of the amount of time spent by each gas molecule or atom within the chamber volume.
2. •
   The time period in which personnel may remain in a restricted area of a reactor before accumulating a certain permissible occupational dose.
3. •
   (no longer used, old-fashioned) Something that halts or arrests the passage of time.