The word "坠落" is formed through the combination of two characters, "坠" and "落", which both independently mean "to fall" or "to drop". This is a classic example of a binomial compound where two synonymous or nearly synonymous morphemes are paired together to create a single, reinforced concept. The pairing intensifies and completes the imagery of the action, with "坠" often carrying a connotation of a heavier, more sudden, or catastrophic fall, while "落" suggests the broader, more general action of descending or alighting. Together, they form a cohesive and vivid depiction of the act of falling, emphasizing both the momentum and the finality of the descent.