This term is generally used as an adjective to Compiler. A JustInTime Compiler defers compilation until RunTime, when a part of the SourceCode actually has to be run. In practice, a JIT Compiler is always part of a VirtualMachine, although the concept is theoretically applicable outside VirtualMachines as well.
With a JIT Compiler, RunTime and CompileTime are interwoven.
3 pages link to JustInTime:
