Definition of martyr:
(n) :
one who takes action according to his religious beliefs accepting that he will be killed by others; one who is put to death for his religion; as, Stephen was the first Christian martyr; hence, one who sacrifices his life, his station, or what is of great value to him, for the sake of principle or to sustain a cause
"stephen was a martyr to arthritis."
(v) :
to put to death for adhering to, or acting in accordance with, some belief, especially religious; to sacrifice on account of faith or profession; to persecute; to torment; to torture