missing time

noun2

1. •
   A time period of amnesia or a gap in conscious memory reported by individuals who have experienced alien abduction.

   • The report of abduction, the memory loss, the missing time, and the shape of the UFO are all familiar to UFO investigators, for this is not an isolated episode. — 1978
2. •
   An operational metric which measures the total amount of time on a timeclock that is unassigned to any task, whether productive or not.