Lisp is a programming language.

Not just any programming language, but, one of the oldest and—IMNSHO—best ones.

 Quote:
Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp (link).


One of the cool things about Lisp is that there is no formal difference between its data structure, the list, and a program. It is quite easy to write programs that write programs, etc.

Ceci n'est pas un seing.