The term martyr (Greek μάρτυς "witness") initially signified a witness in the forensic sense, a person called to bear witness in legal proceedings. With this meaning it was used in the secular sphere as well as in both the Old Testament and the New Testament of the Bible. The process of bearing witness was not intended to lead to the death of the witness, although it is known from ancient writers (e.g. Josephus) that witnesses, especially of the lower classes, were tortured routinely before being interrogated as a means of forcing them to disclose the truth. During the early Christian centuries, the term acquired the extended meaning of a believer who witnesses to his or her religious belief and, because of this witness, endures suffering and death. The term in the English language is a loanword and used only with the extended meaning of someone who has been killed for his religious belief. The death of a martyr or the value attributed to it is called martyrdom.
In the context of church history, from the time of the persecution of early Christians in the Roman Empire, being a martyr indicates a person who is killed for maintaining his or her religious belief, knowing that this will almost certainly result in imminent death (though without intentionally seeking death). Christian martyrs sometimes declined to defend themselves at all, in what they saw as a reflection of Jesus' willing sacrifice. However, the definition of martyrdom is not specifically restricted to the Christian faith.