Passover is the Jewish festival that commemorates the Exodus event (whether you think there was an Exodus or not is a different question, that’s what it commemorates). The name derives from Exodus 12:13 (וּפָסַחְתִּ֖י עֲלֵכֶ֑ם) ‘I will pass over you’, and the verb pesach, which explains most of the terms for Easter that derive from Pesach (Pascha, etc..) which I’ll come back to. In antiquity it was closely associated with the Feat of Unleavened Bread. It’s time of observance was 14th Nisan, which normally falls in April-May. Earlier or alternate origins for Passover are sometimes speculated, but there is a lack of good evidence about Passover’s origins, let alone non-Biblical origins.

Easter is the Christian festival that commemorates the death and resurrection of Jesus. It generally (Depending on calendars and church traditions) coincides with Passover because the NT texts record the tradition that Jesus was put to death at Passover. Thus the calculation of the date of Easter continues to follow the lunar calendar. The second century Quartodeciman controversy saw one group observe Easter on the 3rd day after 14th Nisan, which could be any day of the week, whereas other groups choose to observe it on the first Sunday after the first full moon after the Spring Equinox. This keeps is in sync with Passover and a lunar calendar, but always falling on the Sunday. It was the latter practice that was agreed to at the Council of Nicaea in 325 and dominated in Western churches from then on.

The term ‘Easter’ is widely agreed, in English, to come from Old English Ēostre or Ēastre, an Anglo-Saxon goddess. This appears to be a situation where the co-incidence of a pagan practice with a Christian one lead to the adoption of the name of the pagan practice for the Christian one. It does not really suggest that Easter has a pagan origin, since Easter doesn’t originate in an Anglo-Saxon context at all. Bede the Venerable is a source that suggests that the feasts of Ēostre have been replaced by those of Pascha, thus the meaning of the word ‘Easter’ has shifted.

I am almost certain we will have a question about the pagan origins of Easter in the next week, and the answer is no. Were there pagan festivals that occurred around the spring equinox that may have influenced certain Easter traditions? Certainly, but they are not an origin account for the practice of Easter in Christianity.

So, obviously, ‘Easter’ is a term in English that derives from the history of Christianity in England, but this is not relevant in other languages, which is why most languages use a term that is derived from Pesach in some way to indicate Easter.