Diffuser meaning : Any person or thing that diffuses. A device designed to diffuse a scent efficiently. Any device that or spreads out or scatters light, making the light appear softer. A shaped section of a car's underbody which improves the car's aerodynamic properties. A mechanical device that is designed to control the characteristics of a fluid at the entrance to a thermodynamic open system. (sewage treatment) An aerating device consisting of a membrane with fine pores, through which air is blown to generate small bubbles. A cooking item that can be placed above a stove heating element or burner to separate the cooking utensil from the heat source. A hairdryer attachment that diffuses the flow of air.