The name Jeshurun in the Bible
Jeshurun is a poetic nickname for Israel (Deuteronomy 32:15; Isaiah 44:2). This name shows that once upon a time, before the Masoretic pronunciation aids, the letters שׁ and שׂ were once quite the same: ישׁרון (Jeshurun) or ישׂראל (Israel).
Etymology of the name Jeshurun
The name Jeshurun comes from ישר (yasar) meaning to be level, straight, upright:
The name means Uprighter. Or perhaps, if we serve the marriage-metaphor: Erector! Another nickname for Israel is Zion.
For a meaning of the name Jeshurun, NOBSE Study Bible Name List reads Upright One. Jones' Dictionary of Old Testament Proper Names reads Upright.