Some people questioned if the term "Easter" was of non-christian pagan origin.
I've encountered this issue a couple of times lately. And now thanks to this article at Christianity Today, I can generally summarize the issue:
The word "Easter" is traced to old English (Eostre) and German (Ostern). It is usually referring to the month of April, Eosturmonath (Eostre Month) according to Germanic calendar.
Venerable Bede, historian and English monk of the 7th century, appears to be the only source and claim that Eostre was the name of a goddess in Norse mythology. While Professor Ronald Hutton, 20th century British historian, intreprets the ancient term as "The Month of Opening".
The 1611 KJV Bible uses "Easter" in Acts 12:4 while other versions (NKJV, MKJV, NASB, NIV, etc.) use "passover". Original term being Pascha (Greek) or Pesach פסח in Hebrew.
Conclusion:
There's no ground even for Bede supporters or Christian attackers to say that the celebration of Easter Sunday is of pagan origin. It doesn't even share the same cause with the origins of other Pagan-Christian festivals such as Christmas or Halloween.