What term describes the action of falling down?

The term "collapse" specifically refers to the complete and often sudden failure or breakdown of structure, support, or stability, which can lead to a falling down action. It implies a loss of support and can convey a sense of abruptness and often finality to the action. This term is commonly used in contexts where the entire configuration or integrity of an object gives way under stress or pressure, resulting in a downward movement.

In contrast, "descend" relates to the general act of moving downward but does not necessarily imply any failure or breakdown. "Drop" refers to the action of letting something go, resulting in a downward movement, but it often implies a deliberate release rather than a collapse. "Plummet" indicates a rapid and uncontrolled fall, usually from a height, but, while dramatic, it does not capture the full context of structural failure that is inherent in the term "collapse." Therefore, "collapse" best captures the specific action of falling down due to a failure of support.