What's it called

Is there a term for a type of program that is guaranteed to always produce the same output?  For example, it never accepts keyboard input, never reads a timer, etc, so it must always follow the same execution path.

The only term that comes to mind is "deterministic" but that's not quite right.

>>3
Funny you should say that...  My motivation for asking was thinking about writing a compiler that let you declare certain sections of your code as "idempotent" (now that I know the term) and having it actually execute these sections of code at build time.