🔼The name satan in the Bible
The qualities and character of the creature known as satan are almost all debatable. He is thought to be a cherub or ex-cherub but there's very little proof of that, and he's been expelled from heaven (Job 1:6, Revelation 12:9). We know that he led an insurrection, but it is highly unlikely that his following is organized in the way that God's following is organized. Suffice to say that he poses no threat to God and is certainly not an equal counter-pole.
Christ's victory over satan at His resurrection is a victory obtained for mankind. There is no indication that God and satan ever came to blows personally. Satan is not omnipresent and not omnipotent or omniscient. He has no ability to create, and indications are myriad that he is not even able to govern or manage any large number of creatures (see our all-telling article on the name Beelzebub).
Nothing that is commonly ascribed to satan (darkness, fire, evil) actually belongs to satan, as everything belongs to God; the entire world (Psalm 24:1), and all souls (Ezekiel 18:4). And believe it or not: even the name Lucifer does not belong to satan.
The functional essence of satan may even have originated in a true purpose; the trying and hence actualizing of the potential of God's creation. In the Book of Job (which in itself is monstrously complicated and difficult to place, especially chronologically) satan is still allowed an audience with God and God renders him a specifically limited authority to try Job. Satan goes at it and doesn't cross the line, and perhaps this is why satan is not rebuked in the Book of Job. In stead, in the conclusion of Job's story it reads, "...they consoled him and comforted him for all the evil that the Lord had brought on him".
The events surrounding the Fall Of Man (Genesis 3) may be understood as satan violating a specific limitation set by God: see what they'll come up with but don't make them feed off the Tree Of Knowledge Of Good And Evil. What exactly went wrong we don't know, but satan became proud and may have even tried a coup against God. The arch-angel Michael (means Who Is Like God? Or: What's God Like?) engaged satan and his squad and cast them out.
These things are very difficult and are certainly not easily explained in any common terms. (What may help is to imagine heavenly causality to rest upon space-time causality the way a cube sits on a flat square that forms one of its sides.)
Finally we note that satan has a much larger and romantic and defined role in general culture than in the Bible, and we stress again that the Bible certainly does not support the dualistic idea that the realm of darkness eternally battles the realm of light. Satan is not God's counter-pole.
🔼Etymology of the name satan
The name satan, שטן (satan) is identical to the noun שטן (satan) meaning adversary:
For a meaning of the name satan, NOBSE Study Bible Name List reads Adversary. Jones' Dictionary of Old Testament Proper Names does not translate.