adjective
Definition: Having a relationship in size, amount, or degree with something else; when two things change together in a consistent way.
Example: The amount of water in the tank is proportional to the amount of rainfall.
noun
Definition: A part or amount that is related to another quantity in a specific way, often used in mathematics to describe how two things are connected in size or amount.
Example: In a proportional relationship, if one quantity increases, the other quantity also increases at a consistent rate.