Jezer: the third of Naphtali's four sons, and the ancestor the Jezerite clan was named after
TranslatabilityApproximateCertaintySettled
Jezer belongs entirely to lists. He is named as the third son of Naphtali when Jacob's household goes down to Egypt, he stands at the head of a clan in the wilderness census a generation later, and he appears once more in the short tribal list in Chronicles, which adds that he and his brothers were the sons of Bilhah. He never speaks and never acts. What the Bible reports about him is his father, his brothers, and the family that carried his name.
The name itself is the ordinary Hebrew word for something formed or shaped (יֵצֶר), built from the verb used of a potter working clay (יָצַר). A Hebrew listener heard the meaning at once, something close to "Formed" or "Shaped one," and probably heard a quiet compliment in it: this child is somebody's handiwork. Short names of this kind are common in Hebrew, and many of them are clipped versions of a longer name that once said outright which God did the forming. The English spelling "Jezer" keeps the man and loses all of that.
The three lists agree about him and wobble around him:
Genesis and Chronicles give Naphtali's four sons in the same order, with Jezer third.
The census in Numbers turns each son into a clan, so Jezer becomes the Jezerites (יִצְרִי), a clan word built straight off his name.
Chronicles calls the youngest brother Shallum where Genesis and Numbers call him Shillem, and spells the oldest brother's name a little differently again, while Jezer's name holds steady in all three.
In Hebrew the name is a see-through word for something formed or shaped, so a Hebrew reader heard a meaning and not just a label.Gen 46:24
The Hebrew shows the clan name growing visibly out of the man's name in the same verse, which is why the census can move from the person to the family without explaining anything.Num 26:49
Both
Both name the same third son of Naphtali, and English Bibles carry the name through all three of his appearances unchanged.1Ch 7:13
Only Jezer
In English the name carries no meaning at all, so nothing signals that it is an ordinary word about being shaped or made.
The English spelling suggests no link to the clan called the Jezerites beyond the first few letters, while in Hebrew the two words are plainly the same word.
How yetser differs from similar Hebrew words
יִצְרִיthe Jezerites, the clan named after Jezer, formed straight off his name and appearing in the same census verse that lists him.
Names one man, the third of Naphtali's four sons, counted as an individual among the people who went down to Egypt with Jacob's household.Gen 46:24
Still holds a slot in the tribal family tree long afterward in Chronicles, where it marks a person in a line of descent traced through Bilhah rather than a group of people.1Ch 7:13
Both
Both point to the same branch of Naphtali, and the family word is simply the man's name with an ending added, so the census can move from the ancestor to his descendants inside a single line without explaining the link.Num 26:49
Neither word is ever used of anyone outside this one family. Both turn up only in lists of Naphtali's descendants, so both are read as "Jezer" in English translations, one as the man and one as the people named for him.Gen 46:24Num 26:49
Never names a person. It names a whole family counted as one unit in the wilderness census, so the word is about a body of people and their share in the tribe, not about the ancestor himself.Num 26:49
יִצְרִיIzri, one of the temple musicians appointed in David's day, whose name is written in Hebrew exactly like the clan word for the Jezerites but belongs to a different man in a different tribe.
יָצַרthe verb for forming or shaping something, the potter's word, which is the root the name Jezer is built on.
נַפְתָּלִיNaphtali, Jezer's father and the tribe his clan belonged to; every appearance of Jezer sits inside a list of Naphtali's sons or clans.
BDB, HALOT and DCH each register this form as a personal name distinct from the homographic common noun, attested only at Genesis 46:24,Numbers 26:49 and 1 Chronicles 7:13, with the derived clan designation יִצְרִי at Numbers 26:49. Morphologically it is a segolate of the qetel pattern from the root יצר, form or shape, the same formation as the common noun; the lexica record no textual or semantic difficulty in any of the three attestations. Onomastic study treats it within the large class of short (hypocoristic) Hebrew personal names in which the divine subject of a sentence name is left unexpressed, so that the bare verbal idea stands as the name: Noth's standard treatment situates such formations within the common Semitic naming stock, and Fowler's later catalogue documents the same abbreviating pattern across the Hebrew corpus. The three lists are related literarily rather than independently: Wenham on the Genesis 46 roll and Levine on the Numbers 26 census note that the census clan list reworks the Genesis name list into the administrative units that underwrite the land allotment of Numbers 26:52-56, while Japhet and Knoppers observe that the Chronicler's Naphtali notice is exceptionally brief and drawn from Genesis 46:24, differing only in the orthography of the first name (יַחֲצִיאֵל for יַחְצְאֵל) and in reading שַׁלּוּם for שִׁלֵּם. The name יֵצֶר itself is stable across all three witnesses, and no proposal to emend or redivide it has gained currency.
In-depth research
This is a research paper, so it may be hard to read without scholarly background. It is useful if you want to dig even deeper into this word.
Sources
BDB, A Hebrew and English Lexicon of the Old Testament (Clarendon, 1907), 428, s.v. יֵצֶר (proper name)lexicon
L. Koehler and W. Baumgartner, The Hebrew and Aramaic Lexicon of the Old Testament (Brill, 1994-2000), s.v. יֵצֶר IIlexicon
David J. A. Clines, ed., The Dictionary of Classical Hebrew, vol. 4 (Sheffield Academic Press, 1998), s.v. יֵצֶר IIlexicon
Martin Noth, Die israelitischen Personennamen im Rahmen der gemeinsemitischen Namengebung, BWANT 46 (Kohlhammer, 1928)monograph
Jeaneane D. Fowler, Theophoric Personal Names in Ancient Hebrew: A Comparative Study, JSOTSup 49 (JSOT Press, 1988)monograph
Gordon J. Wenham, Genesis 16-50, WBC 2 (Word, 1994), ad 46:8-27commentary
Baruch A. Levine, Numbers 21-36, Anchor Bible 4A (Doubleday, 2000), ad 26:48-51commentary
Sara Japhet, I and II Chronicles, Old Testament Library (Westminster John Knox, 1993), ad 7:13commentary
Gary N. Knoppers, I Chronicles 1-9, Anchor Bible 12 (Doubleday, 2004), ad 7:13commentary