Jeshurun · Smith

(supremely happy), and once by mistake in Authorized Version JESURUN, (Isaiah 44:2) a symbolical name for Israel in (32:15; 33:5,26; Isaiah 44:2) It is most probably derived from a root signifying "to be blessed." With the intensive termination Jeshurun would then denote Israel as supremely happy or prosperous, and to this signification the context in (32:15) points.

Smith’s Bible Dictionary, William Smith (1863). Public domain, from the CrossWire SWORD module.