A witness. One who accepts death in preference to renunciation of a faith, cause or principle.
Rev_12:11 And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death. An overcomer is never double-minded; but always stands for truth --no matter what the cost.
Matthew 10:28 And fear not them which kill the body, but are not able to kill the soul: but rather fear him which is able to destroy both soul and body in hell.