Scratchpad I
A general-purpose language originally for interactive symbolic mathematics by Richard Jenks, Barry Trager, Stephen M. Watt and Robert S. Sutor of IBM Research, ca 1971. It features abstract parametrised data types, multiple inheritance and polymorphism. There were implementations for VM/CMS and AIX.
["Scratchpad User's Manual", RA 70, IBM (June 1975)].