Wiktionary
n. 1 A person (living or dead) from whom an organ is removed in order to be transplanted into another person. 2 (context chiefly US slang English) A motorcyclist, especially one who does not wear a protective helmet.
WordNet
n. someone from whom an organ is taken for transplantation
Usage examples of "organ donor".
She never signed an organ donor card and we never talked about it.
The chest of Enzo Bandello, legally dead organ donor, heaved massively.
Lacking an identical twin, your chances of a successful transplant are best if your organ donor is a close relative.
I called the hospital, and they'd not been advised that she was an organ donor.
Directing her gaze at Daphne, she said, Did you know it was your father who fought for an organ donor counselor at General?
New cars, old cars, smashed cars, rusted cars, cars that had signed on for the vital organ donor program.