'apocatastatic' ultimately derives from Greek 'apokatastasis' (ἀποκατάστασις) via Late Latin, with the adjective formed by adding the English/Latin adjectival suffix '-ic'.

'apokatastasis' comes from Greek 'apo-' (ἀπό, 'away/from/back') + 'katastasis' (κατάστασις, 'a setting/condition/restoration'); the theological noun entered Late Latin and then English, and later the adjective 'apocatastatic' was formed in English by adding '-ic'.

Originally the Greek term meant 'a restoring or re-establishing' (a return to a former state); over time it became specialized in theology to denote the doctrine of universal restoration (apocatastasis), and 'apocatastatic' now commonly refers to that theological sense or, archaically, to anything restorative.