A widebody trijet airliner produced by McDonnell Douglas, and, later, Boeing, from 1988 through 2000.
The McDonnell Douglas MD-11 is a three-engine widebody jetliner produced by mcdonnell-douglas from 1988 until 1997, and thereafter by boeing until 2000. It was derived from, and intended to serve as a successor to, the dc-10; the two aircraft are very similar, although the MD-11 incorporated a number of incremental advances (foremost among these being a larger fuselage and wing, now equipped with winglets, and a smaller horizontal-stabilizer) and a few more substantial improvements, such as the use of composite-materials for large parts of the aircraft, and the switch to a modern "glass cockpit" (using electronic screens instead of ye olde buttons and dials), which eliminated the need for a flight-engineer and made the MD-11 the first (and only) McDonnell Douglas widebody built with a two-person cockpit (although many of the surviving DC-10s have since been retrofitted with the new cockpit as well, and redesignated "MD-10").
Development of a new and improved DC-10 started in 1976, under the "DC-10 Super 60" name, and proceeded in fits and starts for the better part of a decade at a time when confidence in the DC-10 had been severely shaken by a number of catastrophic accidents stemming from multiple serious design flaws in the DC-10. After two separate stop-work orders in the late 1970s and early 1980s, the design of the MD-11 emerged in more or less its final form in 1984, when DC-10 sales were recovering (somewhat), as was the company's willingness to embark on new projects. McDonnell Douglas was, however, still very far from rolling in cash, and the MD-11 was still essentially an updated DC-10 (unlike the big twinjets boeing and airbus had in the pipeline, which would become the boeing-777 and airbus-a330 just a few years after the MD-11 hit the shelves).
When the MD-11 entered service in December 1990 (having made its first flight that January), it proved to be a dog, with performance much worse than advertised. It took until 1995 before the MD-11 was capable of anything near what had been promised, and, by then, it was too late to save the aircraft; both the 777 and A330 (and the latter's four-engine sister, the airbus-a340) were available by then (offering better performance and lower fuel burn than the MD-11), and, just two years later, McDonnell Douglas merged with Boeing, who ended production of passenger MD-11s as soon as those already under construction were finished and delivered. MD-11 freighters remained in production until 2000, with the very last one delivered to lufthansa in February 2001.
Obsolete almost as soon as it entered service, the MD-11 sold only 200 aircraft (the DC-10 had sold 386, despite a reputation tainted by several fatal crashes), and airlines started phasing them out almost as soon as they were delivered, although a few hung on for years (the last passenger flight by an MD-11 was made by KLM on 11 November 2014). The MD-11's real niche proved to be the cargo airlines, for whom all 121 surviving examples fly; over three-quarters of this total are owned and operated by FedEx and UPS (57 and 37 aircraft, respectively).
For more information about the MD-11, see Wikipedia.