Adam Clarke on Isaiah 44:2

Jesurun - Jeshurun means Israel. This name was given to that people by Moses, Deu 32:15; Deu 33:5, Deu 33:26. The most probable account of it seems to be that in which the Jewish commentators agree; namely, that it is derived from ישר yashar, and signifies upright. In the same manner, Israel, as a people, is called משלם meshullam, perfect, Isa 42:19, They were taught of God, and abundantly furnished with the means of rectitude and perfection in his service and worship. Grotius thinks that ישרון yeshurun is a diminutive of ישראל yishrael, Israel; expressing peculiar fondness and affection; Ισραηλιδιον, O little Israel.