(CLOS) An object-oriented extension to Common LISP, based on generic functions, multiple inheritance, declarative method combination and a meta-object protocol. A descendant of CommonLoops and based on Symbolics FLAVORS and Xerox LOOPS, among others.

See also PCL.

["Common LISP Object System Specification X3J13 Document 88-002R", D.G. Bobrow et al, SIGPLAN Notices 23 (Sep 1988)].