|Easton's Bible Dictionary|
A poetical name for the people of Israel, used in token of affection, meaning, "the dear upright people" (Deuteronomy 32:15; 33:5, 26; Isaiah 44:2).
Int. Standard Bible Encyclopedia
je-shu'-run, jesh'-u-run (yeshurun, "upright one," Deuteronomy 32:15; Deuteronomy 33:5, 26 Isaiah 44:2): Septuagint translates it "the beloved one" egapemenos, the perfect participle passive of agapao), and in Isaiah 44:2 adds "Israel"; Vulgate (Jerome's Latin Bible, 390-405 A.D.) has dilectus in Deuteronomy 32:15, elsewhere rectissimus; Aquila, Symmachus, Theodotion have "upright." For the form, Duhm compares zebhulun, Zebulun.
(1) The name used to be explained as a diminutive form, a pet name, and some, e.g. Cornill, Schultz (Old Testament Theology, English translation, II, 29, note 12) still explain it so, "the righteous little people." But there is no evidence that the ending -un had a diminutive force.
(2) Most moderns take it as a poetical or ideal title of Israel, derived from yashar, "upright"; it is held to contain a tacit reference to the word Israel (yisra'el), of which the first three consonants are almost the same as those of "Jeshurun"; in Numbers 23:10 the term "the righteous ones" (yesharim) is supposed to contain a similar reference. Most commentators compare also "the Book of Jashar," and it has been held that "Jashar" is similarly a name by which Israel is called.
Following Bacher (ZATW, 1885, 161;), commentators hold that in Isaiah this new name, a coinage due to the author of Second Isaiah and adopted in Deuteronomy, stands in contrast to Jacob, "the supplanter," as his name was explained by the Hebrews (compare Hosea 12:2-4). Israel is here given a new name, "the upright, pious one," and with the new name goes new chance in life, to live up to its meaning. Driver (Deuteronomy, 361) says that in Deuteronomy 32:15 "where the context is of declension from its ideal (it is) applied reproachfully. `Nomen Recti pro Israele ponens, ironice eos perstringit qui a rectitudine defecerant' (Calv.). Elsewhere it is used as a title of honor." the King James Version has "Jesurun" in Isaiah 44:2.
David Francis Roberts
Jeshurun (4 Occurrences)
Deuteronomy 32:15 But Jeshurun grew fat, and kicked. You have grown fat. You have grown thick. You have become sleek. Then he forsook God who made him, and lightly esteemed the Rock of his salvation. (WEB KJV JPS ASV BBE DBY WBS YLT NAS NIV)
Deuteronomy 33:5 He was king in Jeshurun, When the heads of the people were gathered, All the tribes of Israel together. (WEB KJV JPS ASV BBE DBY WBS YLT NAS NIV)
Deuteronomy 33:26 "There is none like God, Jeshurun, who rides on the heavens for your help, In his excellency on the skies. (WEB KJV JPS ASV BBE DBY WBS YLT NAS NIV)
Isaiah 44:2 This is what Yahweh who made you, and formed you from the womb, who will help you says: "Don't be afraid, Jacob my servant; and you, Jeshurun, whom I have chosen. (WEB JPS ASV BBE DBY YLT NAS NIV)