What term is used to describe something that is designed to be impervious to human error?

The term that describes something specifically designed to be impervious to human error is "foolproof." This term suggests that the system, process, or design has been created in such a way that it minimizes the possibility of mistakes or failures due to human intervention. In contexts such as product design, safety measures, or software development, a foolproof design ensures that even if a user makes a mistake, the outcome will not lead to adverse effects or catastrophes.

The other terms do not fit this specific definition. "Flamboyant" refers to something that is overly elaborate or showy, often used to describe styles that attract attention. "Fragile" indicates something that is delicate and easily broken, which is the opposite of being resilient against errors. "Forfeit" relates to losing the right to something, often as a penalty, and does not connect to the concept of preventing human error. Thus, "foolproof" is the clear choice in this context.