One who dies for not denying their faith in Christ; some die just for having it. Seen as a relic of centuries past, when Christianity was, out of necessity, practiced underground, and being outed as a Christian meant persecution (if you were lucky) or death. But the 20th Century has been a "century of martyrs", the killing having moved, of late, to the Third World. In some places, it's just unsafe to be a missionary; even if you're widely loved, it only takes one person, one bullet...