'pro-charity' is a modern compound formed from the prefix 'pro-' (from Latin 'pro' meaning 'for, in favor of') + the noun 'charity' (from Old French 'charité', ultimately from Latin 'caritas').

'charity' came into English via Old French 'charité' from Latin 'caritas'; the prefix 'pro-' comes directly from Latin 'pro' meaning 'for'. The combination into a hyphenated compound 'pro-charity' follows modern English patterns of prefixing 'pro-' to nouns to indicate support.

The element 'pro-' originally meant 'for' or 'in front of'; combined with 'charity', the compound's meaning has become 'in favor of charity' as a descriptive stance or label.