What term fits the definition "Restrictions or limitations on the solutions"?

The term that fits the definition "Restrictions or limitations on the solutions" is constraint. In the context of requirements and solutions, constraints signify the boundaries within which a solution must operate. These can include technical limitations, regulatory policies, budget restrictions, time constraints, or any other specific conditions that must be adhered to when designing a solution.

Constraints are crucial for guiding the development process and ensuring that the end product meets not only functional requirements but also operates under acceptable parameters. Understanding constraints helps stakeholders navigate the trade-offs involved in decision-making, as they delineate what is feasible and permissible in the context of the project.

In contrast, while an interface refers to the point of interaction between different systems or components, risks pertain to potential issues that might arise during the course of a project, and assumptions involve beliefs or statements taken for granted without required proof. These terms, although relevant in requirement analysis, do not directly represent the idea of restrictions on solutions as effectively as constraints do.