'post-Communion' originates from Latin elements, specifically 'post' and 'communio' (or the accusative 'communionem'), where 'post' meant 'after' and 'communio' meant 'sharing' or 'communion'.

'post-Communion' developed via Medieval and Ecclesiastical Latin usage (e.g. 'postcommunionem') into later liturgical English forms such as 'post-Communion' or 'postcommunion', used to name the prayer or the period following Communion.

Initially it referred broadly to 'after the act of sharing/communion' in Latin contexts, and over time it became a specific liturgical term for the prayer or rites following Communion in Christian worship.