What term describes a sudden loss of power, happiness, or success?

The term that best describes a sudden loss of power, happiness, or success is "downfall." This word encapsulates the idea of a dramatic change from a high position or state to one of significantly reduced status or fortune. A downfall often implies a more comprehensive and impactful event than just a simple loss, as it suggests that one has fallen from a previously held height, whether it be in social standing, emotional well-being, or achievements.

In literary contexts, downfall can refer to characters who experience significant reversals of fortune, illustrating themes like tragedy and the fragility of success. This term conveys both the abruptness of the change and the severity of its consequences for the individual or entity involved, making it particularly relevant for discussing character arcs or the message of a narrative.

The other terms, while related, do not fully capture the same gravity or specific nuance associated with an abrupt and total loss in the same way "downfall" does. For instance, "collapse" might suggest a physical or structural failure, "failure" implies a lack of success without necessarily conveying a previous high state, and "decline" often indicates a gradual process rather than a sudden shift.