Satan is a Hebrew word meaning adversary, opponent, accuser. It is sometimes translated "Satan," as in Psalm 109:6 in the KJV, and sometimes "accuser," as in the New King James Verson and the Revised Standard Version of the same passage.
Zechariah 3:1 in the RSV says, "Satan standing at his right hand to accuse him." The words "Satan" and "accuse" here are the same.
In the New Testament, the word "Satan" is simply a Greek transliteration of the Hebrew word. It means "the accuser."
The word "devil" in the Greek is diabolos. It means a traducer or false accuser. Traduce means to disgrace, to defame, to slander. Slander is the oral utterance or spreading of a falsehood, harmful to another's reputation; libel.
The Greek word translated "false accusers" in 2 Timothy 3:3 is translated "devil" just three verses earlier in 2 Timothy 2:26.