A  is a solid form of a medication mixed with solution; usually it must be shaken well before use.

The description you're providing pertains to a "suspension."

A suspension is a type of solid-liquid mixture in which fine solid particles are dispersed in a liquid. In medical contexts, suspensions are often used for medications that are insoluble or poorly soluble in the solvent, allowing for a more effective delivery of the drug. The need to "shake well before use" is crucial because it ensures that the solid particles are evenly distributed throughout the liquid, which is important for dosage accuracy and effectiveness.

When a suspension is left to stand, the solid particles may settle at the bottom, leading to uneven distribution of the medication. Thus, shaking or mixing redistributes the particles, making sure that each dose contains a consistent amount of the active ingredient. This property makes suspensions an important formulation for certain types of medications, particularly in pediatrics, where some patients may have difficulty swallowing pills.