The term 'impeller' is a mechanical device used to create a flow of liquid or gas. It consists of a central hub, blades, and a shaft. The blades are connected to the hub and rotate around the shaft, creating a centrifugal force that pushes the liquid or gas outward. The term 'SPUR' is a four-letter word that can be used to describe an impeller. It is derived from the Latin word 'spurius, ' which means 'to push.' In this context, it refers to the action of the impeller pushing the liquid or gas outward.