diffuser

1. (optics) Any device that or spreads out or scatters light, making the light appear softer.Examples: "Along the sofa every three and a half feet, fluorescent tubes glow through translucent plastic diffusers."

2. (automotive) A shaped section of a car's underbody which improves the car's aerodynamic properties.

3. (thermodynamics) A mechanical device that is designed to control the characteristics of a fluid at the entrance to a thermodynamic open system.

4. (sewage treatment) An aerating device consisting of a membrane with fine pores, through which air is blown to generate small bubbles.

5. (cooking) A cooking item that can be placed above a stove heating element or burner to separate the cooking utensil from the heat source.