'pro-marriage' originates from English, combining the prefix 'pro-' (from Latin 'pro' meaning 'for') and the noun 'marriage' (ultimately from Old French 'mariage' and Latin 'maritare'/'maritus').

'marriage' changed from the Old French word 'mariage' (from Latin 'maritare'/'maritus') and eventually became the modern English word 'marriage'; the prefix 'pro-' comes from Latin 'pro' and was adopted in English as a productive prefix meaning 'in favor of', forming compounds such as 'pro-marriage'.

Initially it was a literal compound meaning 'for marriage'; over time it has been used more widely as an adjective or noun in political and social contexts to denote support for marriage as a policy or stance.