The Greek adjective adynatos is formed from a- (not) + dynatos (G1415, powerful/able), meaning powerless, unable, or impossible. In the Gospels and epistles, it describes things that are humanly or naturally impossible (Matthew 19:26; Romans 8:3), as well as people who are weak or incapable. The word frames one of the most important theological contrasts in Scripture: human powerlessness vs. divine omnipotence.
The gospel hinges on adynatos: what is impossible for humanity, God makes possible. With man this is impossible, but with God all things are possible (Matthew 19:26). The Law was powerless (adynaton) because of sinful flesh (Romans 8:3) — it could diagnose the disease but not cure it. Only the Son, sent in the likeness of sinful flesh, could do what the Law could not. Paul also uses a related form to describe the 'weak' in faith (Romans 15:1), calling the strong to bear with them. The adynatos person is not abandoned by God — they are the very ones Christ came to strengthen.