Judah is Lyddie's and Rachel's uncle. He is the husband of their mother's sister. Judah is mentioned early in the story, but only in passing. However, Uncle Judah is featured more prominently later on, when he drops off Rachel at the boarding house where Lyddie is staying.
In that particular scene, we see the true nature of Judah. He informs Lyddie that the farm must be sold to pay for Lyddie's mother's mental hospital costs. Judah is insistent, despite Lyddie's efforts to dissuade him.
The best word to describe Uncle Judah is "inconsiderate." However, he is not inconsiderate in the sense that he is selfish and thoughtless; he is inconsiderate in that he seems to only have accepted Lyddie and Rachel as family members because of his wife. He is also inconsiderate in that he doesn't show sympathy toward the sisters' plight.