fdefinition

(fdefinition symbol)

The function value of a symbol, like symbol-function (setf-function names are not supported).

A quoted symbol literal ((fdefinition 'car)) resolves at compile time in the compilers; a runtime-computed symbol resolves late through the compiled name registry when the result is called, with the same deviations as symbol-function.

fdefinition is the same setf place as symbol-function: (setf (fdefinition 'name) fn) installs fn as the symbol's global function definition.