AutoLISP

Another member of the Lisp family, AutoLISP is a dialect of that language developed specifically to work within AutoCAD and several of its derivative platforms. That’s why it’s almost exclusively focused on geometry. 

AutoLISP is a dialect of the programming language Lisp built specifically for use with the full version of AutoCAD and its derivatives, which include AutoCAD Map 3D, AutoCAD Architecture and AutoCAD Mechanical. Neither the application programming interface (API) nor the interpreter to execute AutoLISP code are included in the AutoCAD LT product line.