�Unbound� Variables
A symbol that has not been given a value by assignment or in a function call is said to be �unbound.�
ERROR Unbound variable NEWSYMBOL.
The use of �unbound� here is actually a misnomer, because NEWSYMBOL has a binding. The binding just doesn�t have any value. But old uses of terminology persist!
> (makunbound 'newsymbol); undo the assignment