This is really two words, but they form a phrase that is used over and over again in the story, so I will discuss them together. jatarūn refers to something that is seen, is in sight, is visible, etc. jawēha is the inanimate singular of anwēha which is the attribute “false, deceptive”. Together, jatarūn jawēha (or jatarūna jawēha, same thing) refers to a mirage.
ē ñi ancālli tō malō aþ ñamma jatōna jaxōsa jōrre aþ ñi sāen rā jatarūni jawēhi nō;
And the sun’s heat came, and he stopped searching for the road and started following mirages.