Basic Language for Implementation of System Software (or allegedly, "System Software Implementation Language, Backwards"). Designed by W.A. Wulf, CMU ca. 1969.
An expression language, block-structured, and typeless, with exception handling facilities, coroutines, a macro system, and a highly optimising compiler. One of the first non-assembly languages for operating system implementation. Gained fame for its lack of a goto. Also lacks implicit dereferencing: all symbols stand for addresses, not values.
Versions: CMU BLISS-10 for the PDP-10; CMU BLISS-11, DEC BLISS-32 for VAX/VMS.
["BLISS: A Language for Systems Programming", W.A. Wulf et al, CACM 14(12):780-790. Dec 1971].