From the root meaning to be of equal weight on a scale — thus, deserving of, worth, or appropriate to. Axios measures whether something or someone measures up to a standard or is fit for a calling. In Revelation it becomes a cosmic declaration of Christ's unique worthiness.
Revelation 5 is the NT's supreme deployment of axios: the angelic and cosmic declaration 'Worthy (axios) is the Lamb!' Who is worthy to open the sealed scroll — to execute God's purposes in history? No one in heaven or earth — until the slain Lamb steps forward. His worthiness is grounded in his sacrificial death ('you were slain'). This inversion — the Lamb, not the Lion, is worthy — defines NT theology of power and victory.