'pro-clericalism' is formed from the prefix 'pro-' (from Latin 'pro', meaning 'for') combined with 'clericalism' (from 'clerical' + '-ism'), where 'clerical' relates to 'cleric' (a member of the clergy) and '-ism' denotes a doctrine or system.

'cleric' comes from Latin 'clericus' (from Greek 'klerikos'), passed into Old French as 'clerc' and into Middle English as 'clerk/cleric'; 'clerical' developed from these, 'clericalism' arose to denote the influence or authority of the clergy, and the modern compound 'pro-clericalism' formed by adding the prefix 'pro-' to indicate support.

Originally terms like 'cleric' and 'clerical' referred simply to members of the clergy and things pertaining to them; over time 'clericalism' came to mean the political or institutional influence of clergy, and 'pro-clericalism' now specifically denotes support for that influence.