I like YYZ's definition, but ETOPS stands for:
Extended-range twin-engine operations
From the Boeing site:
In 1953, the United States developed regulations that prohibited two-engine airplanes from routes more than 60 min (single-engine flying time) from an adequate airport. These regulations were later formalized in U.S. Federal Aviation Administration (FAA) Federal Aviation Regulation 121.161. The ETOPS program, as outlined in FAA Advisory Circular (AC) 120-42A, allows operators to deviate from this rule under certain conditions. By incorporating specific hardware improvements and establishing specific maintenance and operational procedures, operators can fly extended distances up to 180 min from the alternate airport. These hardware improvements were designed into Boeing 737-600/-700/ -800/-900 and 777 airplanes.
http://www.boeing.com/commercial/aer..._07/etops.html