An Ephraimite that is mentioned in 2 Chronicles 25:7 is a member of the Hebrew tribe of Ephraim. https://www.merriam-webster.com/dictionary/Ephraimite
“According to the Bible, the Tribe of Ephraim is descended from a man named Ephraim. This Ephraim is recorded as the son of Joseph, the son of Jacob. The descendants of Joseph formed two of the tribes of Israel, whereas each of the other sons of Jacob was the founder of only one tribe.”
Much more information about the Tribe of Ephraimite can be found here: https://en.wikipedia.org/wiki/Tribe_of_Ephraim
Also if you read the link above, read the last section about “Destiny.” Some interesting stuff I plan to research in more detail at some point.