'pro-papacy' originates from English combining the prefix 'pro-' (from Latin 'pro') and the noun 'papacy' (from Medieval Latin/French), where 'pro-' meant 'for' or 'in favor of' and 'papacy' referred to 'the office or authority of the pope'.

'pro-papacy' is a modern English compound formed from 'pro-' + 'papacy'. The element 'papacy' itself developed from Old French 'papauté' and Medieval Latin 'pāpātus' (from Latin 'papa', ultimately from Greek 'pappas' meaning 'father'), and became the English 'papacy' in Late Middle English/early Modern English; the prefix 'pro-' has been used since Classical Latin and was productive in English to form compounds meaning 'in favor of'.

Initially the parts signified 'for' + 'the pope's office'; the compound has stayed close to that original sense and means 'support for the papacy' in contemporary usage.