The original LISP was a language and its implementation. It was also documented - see for example the LISP 1 manual and other publications about it. From that a

The original LISP was a language and its implementation. It was also documented - see for example the LISP 1 manual and other publications about it. From that a series of languages evolved, which shared the original core (syntax, data structures, operators, ...) That's what I would consider the core Lisp language family. Most of these languages will have 'Lisp' in its name.