The name Jerahmeel (Hebrew יְרַחְמְאֵל, Greek ιραμεηλ) appears several times in the Tanakh. It means "He will obtain mercy of God" or "God pities" or "May God have compassion".
There are probably three distinct persons of that name in the Tanakh. In order of their lifetimes they are:
The Jerahmeelites were a people, presumably descended from Jerahmeel number 1 above, living in the Negev, who David, while in service with the Philistines, claimed to have attacked (1 Samuel 27:10), but with whom he was really on friendly terms (1 Samuel 30:29).
Cheyne developed a theory which made the Jerahmeelites into a significant part of the history of Israel, but most subsequent scholars have dismissed his ideas as fanciful.
In some deuterocanonical and apocryphal writings there are references to an archangel variously called Jeremiel, Eremiel, Remiel, Ramiel etc. See the article Jerahmeel (archangel).
The Chronicles of Jerahmeel is a mediaeval document ascribed to the 12th century Jewish historian Jerahmeel ben Solomon, and is unrelated to any of the above.
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "". Encyclopædia Britannica (11th ed.). Cambridge University Press.