also known as: κατήγωρκατήγωρ or κατήγωρ or κατήγορος (Greek / transliteration: kategoros), קָטִיגור (Hebrew), the accuser of men before God, the accuser of the brethren, prosecutor, adversary
Satan was regarded by the Jews as the accuser of men before God, laying to their charge the violations of the law of which they were guilty, and demanding their punishment.
Satan seeks to uphold his influence among men by bringing false charges against Christians, with the purpose of weakening their influence and injuring the cause with which they are identified. The apostle John heard an angel called Satan “the accuser of the brethren”…
And I heard a loud voice saying in heaven, “Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night.” —Revelation 12:10 KJV
Zechariah the prophet reports…
Then he showed me Joshua the high priest standing before the angel of the Lord, and Satan standing at his right hand to accuse [Hebrew: לְשִׂטְנֽוֹ] him. —Zechariah 3:1 NASB
Compare to the record in the Book of Job…
Now there was a day when the sons of God came to present themselves before the Lord, and Satan also came among them. The Lord said to Satan, “From where do you come?”
Then Satan answered the Lord and said, “From roaming about on the earth and walking around on it.”
The Lord said to Satan, “Have you considered My servant Job? For there is no one like him on the earth, a blameless and upright man, fearing God and turning away from evil.”
Then Satan answered the Lord, “Does Job fear God for nothing? Have You not made a hedge about him and his house and all that he has, on every side? You have blessed the work of his hands, and his possessions have increased in the land. But put forth Your hand now and touch all that he has; he will surely curse You to Your face.” —Job 1:6-11 NASB
Greek: κατηγόροις (transliteration: katēgoroi) —meaning: “accusers”
The same Greek word κατήγοροί, translated “accuser” or “accuse” is found in John 8:10 (but omitted in the Revised King James Version); Acts 23:30, 35; 24:8; 25:16, 18. In each case it refers to one who brings a charge against another.