Which term best describes a plan or creation conceived as a solution to a problem?

The term that best describes a plan or creation conceived as a solution to a problem is design. Design encompasses the process of identifying a problem, conceptualizing solutions, and systematically outlining how to implement those solutions. It involves understanding user needs, functionality, aesthetics, and viability, allowing for a structured approach to creating solutions that address specific issues.

In contrast, invention typically refers to the creation of something new that did not previously exist, which may not necessarily involve a plan or structured approach. The term concept generally describes an initial idea or notion that may lead to a more developed design but does not imply a complete plan for addressing a problem. Prototype refers to a tangible version of a design created to test and validate ideas; it's a physical manifestation of a design rather than the plan itself. Thus, design is the most encompassing term that accurately represents a structured solution-finding process.