'pre-Passover' is built from the prefix 'pre-' and the noun 'Passover'. The prefix 'pre-' originates from Latin, specifically the word 'prae', where 'prae' meant 'before'. 'Passover' originates from Hebrew, specifically the word 'Pesach', where 'Pesach' meant 'to pass over'.

'Passover' changed from Hebrew 'Pesach' to Greek 'Pascha', then to Latin 'Pascha', later appears in Middle English as forms like 'Pasche' and eventually became the modern English word 'Passover'. The prefix 'pre-' comes from Latin 'prae' and entered English as a productive prefix in post-Classical and Middle English periods.

Initially the elements meant 'before' (from 'prae') and 'Passover' (from 'Pesach'); combined they have consistently meant 'before Passover' and this basic sense has been retained in modern usage.