Next in the list of Lisp features I’m reviewing here is fmakunbound. There isn’t very much to say about this if you understand the behaviour of packages and intern, covered in this earlier article. The fmakunbound function causes the function field associated with the symbol to be discarded. If that symbol formerly had a function field associated with it, allowing the function to be invoked by interpreting the symbol in a function context, then that method of invocation is no longer available.
As with fboundp, fmakunbound does not see lexically scoped symbols, it only acts on the set of interned symbols, so it does not affect behaviour driven by flet, labels, or macrolet.