What type of medication form is a water-based suspension applied to the skin?

A lotion is a water-based suspension designed for topical application to the skin. It typically contains a mixture of water and other ingredients, which can help to hydrate and soothe the skin. By having a water-based formula, lotions are often lighter and can spread easily over larger areas. They are particularly useful for delivering medications or treatments for various skin conditions, allowing for effective absorption while also providing a moisturizing effect.

In contrast, liniments often contain alcohol or other solvents, which may provide a heating or cooling effect typically used for muscle aches or pains but are not primarily water-based. Gels are usually thicker, consist primarily of a gel-like substance, and have different absorption properties. Aerosols are used to deliver medication in a fine mist or spray form and are not typically associated with a water-based suspension for skin application. Therefore, the characteristics of lotions best match the description provided in the question.