🔼The name Aharah in the Bible
There's only one Aharah in the Bible, and, according to 1 Chronicles 8:1, he's the third son of Benjamin, and brother of Bela and Ashbel. In the genealogy of Genesis 46:21, Aharah is not mentioned among the ten sons of Benjamin. But in Numbers 26:38 we find an Ahiram, and BDB Theological Dictionary proposes that Aharah may be a contracted form of that name.
Aharah wasn't present at the migration to Goshen, but the elevation of Aharah's position to number three may be due to inter-familial politics (something similar happened to Jacob and later his son Judah).
🔼Etymology of the name Aharah
The name Aharah seems to be drawn from the very common Hebrew word אחר, meaning after or behind:
Scholars propose that the final heth comes from a word that is a common name-element, namely אח (ah), meaning brother. Although this word seems quite essential and occurs all over the Bible, the origins of this word are unknown:
For a meaning of the name Aharah, NOBSE Study Bible Name List offers After His Brother, and Jones' Dictionary of Old Testament Proper Names reads the more general After A Brother.