one who voluntarily suffers death as the penalty for refusing to renounce their religion
"The church honored him as a martyr after he was beheaded rather than denying his faith during the persecution."
One who willingly accepts being put to death for adhering openly to one's religious beliefs; notably, saints canonized after martyrdom.
"The early Christians were hailed as martyrs when they refused to abandon their faith despite facing execution by the Roman authorities."
To make someone into a martyr by putting him or her to death for adhering to, or acting in accordance with, some belief, especially religious; to sacrifice on account of faith or profession.
"The revolutionaries were quick to claim that the governor had martyred the leader simply because he refused to renounce his faith."
The word "martyr" comes from the Ancient Greek word mártus, which originally meant "witness." It entered English through Old and Middle English as a borrowing from Ecclesiastical Latin.