High Quality Content by WIKIPEDIA articles! Common Lisp, commonly abbreviated CL, is a dialect of the Lisp programming language, published in ANSI standard document ANSI INCITS 226-1994 (R2004), (formerly X3.226-1994 (R1999)). From the ANSI Common Lisp standard the Common Lisp HyperSpec has been derived for use with web browsers. Common Lisp was developed to standardize the divergent variants of Lisp (though mainly the MacLisp variants) which predated it, thus it is not an implementation but rather a language specification. Several implementations of the Common Lisp standard are available, including free and open source software and proprietary products.