The word "紫薇" is formed by combining the character "紫", meaning purple, which is itself composed of the semantic component "糸" (silk, indicating color) and the phonetic component "此", with the character "薇", meaning a type of plant, composed of the semantic radical "艹" (grass, indicating plant category) and the phonetic component "微"; together, they denote the crape myrtle tree, with "紫" referencing its purple flowers and "薇" identifying it as a plant.