1. The elapsed time to perform a computation on a particular computer. 
2. The amount of time a processor actually spent on a particular process and not on other processes or overhead (see 
time-sharing). 
3. The period of time during which a program is being executed, as opposed to compile-time or load time. The term should be hyphenated when used as an adjective. 
4. 
run-time support. 
(2001-09-14)