[DEFINED] [COMPILE] [ELSE]
[DEFINED] word ( -- nfa|0 )   immediate
immediate <PFE-SMART>
does check for the word using find (so it does not throw like ' ) and puts it on stack. As it is immediate it does work in compile-mode too, so it places its argument in the cs-stack then. This is most useful with a directly following [IF] clause, so that sth. like an [IFDEF] word can be simulated through [DEFINED] word [IF]

reference: p4_bracket_defined in ../src/yours.c:0803, export CI [DEFINED]