The word "坠落" is formed by combining the characters "坠" and "落", both meaning to fall. "坠" uses the radical "阝", derived from "阜" and associated with terrain or elevation, implying a downward drop, while "落" includes the radical "艹", related to plants, often conveying the idea of something like leaves falling. Together, they create a compound where each character reinforces the same action, resulting in a word that means to plummet or fall.