The word 不堪入目 is formed by sequentially combining the characters 不 (not), 堪 (to bear), 入 (to enter), and 目 (eyes), creating a literal meaning of "cannot bear to enter the eyes". This constructs a fixed idiomatic expression where 不堪 negates the ability to endure, and 入目 describes the action of entering one's vision, together conveying the figurative sense of something being too ugly or shocking to look at.