'post-Easter' originates from English as a compound of the prefix 'post-' (from Latin 'post' meaning 'after') and 'Easter' (from Old English 'Ēastre').

'post-' comes from Latin 'post' meaning 'after'; 'Easter' comes from Old English 'Ēastre' (possibly named for a goddess Ēostre or the spring festival) and the modern compound 'post-Easter' is a straightforward combination formed in modern English to mean 'after Easter'.

Initially the parts meant 'after' (post-) and the festival 'Easter'; the compound kept these senses and now specifically denotes timing or events after the Easter festival.