King James Bible Dictionary

Satan is styled the "accuser of the brethren" (Revelation 12:10. Comp. Job 1:6; Zechariah 3:1), as seeking to uphold his influence among men by bringing false charges against Christians, with the view of weakening their influence and injuring the cause with which they are identified. He 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. The same Greek word, rendered "accuser," is found in John 8:10 (but omitted in the Revised Version); Acts 23:30, 35; 24:8; 25:16, 18, in all of which places it is used of one who brings a charge against another.

ACCU'SER, noun One who accuses or blames; an officer who prefers an accusation against another for some offense, in the name of the government, before a tribunal that has cognizance of the offense.