'pre-Communion' originates from the Latin prefix 'prae' (as English 'pre-'), specifically the word 'prae', where 'prae-' meant 'before', combined with 'Communion', which originates from Latin 'communio' (from 'communis').

'Communion' passed into English from Old French 'communion', ultimately from Latin 'communio' (from 'communis' meaning 'common'); the productive English prefix 'pre-' (from Latin 'prae-') was later attached in Modern English to form the compound 'pre-Communion'.

Originally 'communion' carried the sense of 'sharing' or 'participation in common'; over time it became specialized in Christian usage to mean the Eucharist, and 'pre-Communion' came to mean 'before the Eucharist'.