Abstract nouns refer to things that do not have physical existence, for instance, wisdom, kindness, generosity to mention but a few. They are mainly formed from other word classes. For example, brother-brotherhood. Now, East is a common noun. So, with suffix added it, change to Easter an abstract noun. Sun rises from east synonymous phrase with a new dawn-a new beginning.
A long time ago, people decided to number the years. They started counting from the year Christ was born. They called that year ‘The first year of Our Lord.’
The early Christians used a language called Latin. In Latin, the words for ‘the year of Our Lord’ are ‘Anno Domini’. So the first year was called 1 Anno Domini. We write that in short, like this : 1 A.D. Or we can write A.D. 1. When talking of years before Christ was born they numbered them backwards and added ‘B.C.’ for ‘Before Christ.
So Easter is the beginning of the post-physical Christ Anno Domini ‘New Testament’ implementation in my viewpoint.