(also wall clock time)
1. ‘Real world’ time (what the clock on the wall shows), as opposed to the system clock's idea of time.
2. The real running time of a program, as opposed to the number of ticks required to execute it (on a timesharing system these always differ, as no one program gets all the ticks, and on multiprocessor systems with good thread support one may get more processor time than real time).