My association with the words
whomsoever
whosoever
has been through the Bible, more modern day they have become
whomever
whoever
As an example, John 13:20
He that receiveth whomsoever I send receiveth me. (King James Version)
he who receives whomever I send receives Me (New American Standard)
The New American Standard version is a more "modern" translation.
When and why did the "so" disappear?
I have tried searching, but can find when/why the change occurred.