Martyr-of uncertain affinity; a witness (literally (judicially) or figuratively (genitive case)); by analogy, a "martyr":-- martyr, record, witness. (Strongs Greek)
Those who die for their faith in Jesus Christ are commonly called "martyrs". They truly are witnesses, their life and testimony shine to those who are persecuting them, to those who witness their suffering, and to those who are left behind.
Please pray for these witnesses for Jesus as they are persecuted and martyred for Him.
"When he opened the fifth seal, I saw under the altar the souls of those who had been slain for the word of God and for the witness they had borne. They cried out with a loud voice, 'O Sovereign Lord, holy and true, how long before you will judge and avenge our blood on those who dwell on the earth?' Then they were each given a white robe and told to rest a little longer until the number of their fellow servants and their brothers should be complete, who were to be killed as they themselves had been." (Revelation 6:9-11 ESV)