The Greek adjective aidios means eternal, everlasting, or existing without end. It appears only twice in the New Testament: Romans 1:20 (eternal power) and Jude 6 (eternal chains). It is distinct from the more common aiōnios (G166, pertaining to the age) in that aidios emphasizes the timeless, unending duration of something — without beginning or end. It was used by Greek philosophers for the eternal nature of the divine.
Paul uses aidios in one of the most important apologetic passages in the New Testament: God's eternal power and divine nature have been clearly seen through creation since the beginning of the world (Romans 1:20). This is Paul's foundation for the universal guilt of humanity — creation itself testifies to the eternal God, leaving no one without excuse. Jude uses aidios for the chains that bind the fallen angels — a sobering reminder that eternal realities cut both ways. The same eternal power that sustains the redeemed holds the rebellious in judgment. Eternity is not neutral; it is the canvas on which every human choice is written permanently.