The word 困难 is formed by combining two characters, each contributing a layer of meaning to create a unified concept. The first character, 困, depicts a tree (木) enclosed within four boundaries (囗), originally conveying a sense of being trapped, beset, or in distress. The second character, 难, which historically represented a bird, is used phonetically here but carries the associated meaning of "hard to do" or "arduous". Together, they create a compound idea where the sense of being constrained or in hardship (困) is intensified by the notion of something being arduous or challenging (难), resulting in the comprehensive meaning of "difficulty" or "hardship".