Proposal

[DEFINED]    "bracket-defined" TOOLS EXT X:defined

Compilation: Perform the execution semantics given below.

Execution: ( "<spaces>name" -- flag )

Skip leading space delimiters.  Parse name delimited by a space.
Return a true flag if /name/ is the name of a word that can be found
(according to the rules in the system's FIND); otherwise return a
false flag.  [DEFINED] is an immediate word.


[UNDEFINED]  "bracket-undefined" TOOLS EXT X:defined

Compilation: Perform the execution semantics given below.

Execution: ( "<spaces>name" -- flag )

Skip leading space delimiters.  Parse name delimited by a space.
Return a false flag if /name/ is the name of a word that can be found
(according to the rules in the system's FIND); otherwise return a true
flag.  [UNDEFINED] is an immediate word.