Firstborn – Bekhor

The “firstborn of the father” receives a “double portion” of the “inheritance” as well as “being the leader” of his “brothers”.

However if a “son other than the firstborn” “receives this inheritance”, “he is called” the “firstborn”.

Interestingly this is a “very common occurrence’ within the “Biblical text” such as we see with “Jacob” and “Ephraim”.

Strong’s: #1060 – https://biblehub.com/hebrew/1060.htm