A motorcycle, particularly one that is extremely powerful and fast. Also: donor-cycle, donor cycle.
In the last five years, the number of riders killed in motorcycle accidents has risen 55 percent, reversing a two-decade trend of declining deaths. There were 3,276 deaths in 2002, according to the Federal Highway Administration. In part, deaths are rising because motorcycling is becoming more popular. There were almost five million motorcycles in the United States in 2001, the most recent year for which data is available, up from 3.8 million in 1998. But even accounting for the increase in riders, motorcycle fatalities are on the rise. The average rider now has about a 1-in-1,500 chance of dying annually, and for every mile of travel, a motorcycle is 26 times as dangerous as a car.
Of course, the risk is not equally divided. Inexperienced riders, especially those who have not taken training courses, are more likely to die. Sport bikes, which emergency-room doctors call "donorcycles," as in organ donation, are more dangerous than their less powerful counterparts.
Alex Berenson, "Born to Be Wild, but at a Cost," The New York Times, July 6, 2003
Organ donors are not just people who die. They are young, healthy people who die unexpectedly usually from a violent accident, suicide or crime, such as a motorcycle crash or a gunshot wound to the head. Transplant surgeons sometimes refer to motorcycles as "donorcycles."
Don Colburn, "Transplants: Who Lives? Who Decides?," The Washington Post, January 20, 1987
As the example citation says, this bit of medical slang is a blend of donor and motorcycle and is based on the grisly fact that a disproportionate number of fatal traffic accidents happen to those who ride sport bikes, those sleek and colorful machines that are really not much more than an absurdly powerful engine bolted to a couple of wheels. (The high accident rate of these bikes has spawned another name for them: suicycles.) Most of those who ride such bikes are young and healthy, which, if their time comes, makes them ideal organ donor condidates.
A reader named "ZenMan" passed along the following tidbit:
With Donorcycles (the movement), bikers have organ donor cards that say their organs can only be donated to states without helmet laws.