So I know what pragma is, and what it's used for, but what is the meaning of the word itself? I've used it many times in code, but I never really knew what the word actually means or stands for.
According to a US Government-owned(!) document describing the design of Ada: Rationale for the Design of the Ada® Programming Language :
A pragma (from the Greek word meaning action) is used to direct the actions of the compiler in particular ways, but has no effect on the semantics of a program (in general).
I like the (last caveat) there...
This cross references well with on-line greek dictionaries (e.g. as quoted by Martin York) that say pragma (πράγμα, as commented on the original question by asveikau) means:
Seems the key to understanding is the word action rather than information.