The Greek verb diasozo means to bring someone safely through danger, to rescue completely, or to preserve through peril. The dia prefix adds the sense of thoroughness — saving all the way through.
Diasozo is used of miraculous physical deliverance — the crowd's hope to touch Jesus and be 'completely healed' (Matthew 14:36), Paul's survival of the shipwreck at Malta (Acts 27:44), and the ark that 'saved' Noah's family through the flood (1 Peter 3:20). The word carries the sense of emergence from danger intact — which is precisely the picture of salvation: not just rescue from hell but bringing us all the way through to glory.