In the main heritage line of Lisp (Lisp 1.5, MacLisp, Lisp Machine Lisp, CL), Common Lisp is still THE common Lisp. One can run run old code from the 1960s with relatively little changes. Neither with Scheme and Clojure you can do that. Both are Lisp dialects. Clojure is basically incompatible with every other Lisp and porting Lisp code to and from Clojure is basically done by completely reimplementing it.
So, Common Lisp is not THE Lisp, but the common Lisp.
So, Common Lisp is not THE Lisp, but the common Lisp.