diffuser

/dɪˈfjuzər/
noun
  1. A device that spreads something out, such as light, sound, or a liquid, over a wider area.
    • A hair diffuser helps dry curly hair without making it frizzy.
    • She put a few drops of lavender oil in the diffuser to make the room smell nice.
    • The photographer used a diffuser on the flash to soften the light.
  2. A part of a machine or system that reduces the speed of a fluid and increases its pressure.
    • Engineers designed a new diffuser for the wind tunnel.
    • The car's rear diffuser helps improve its aerodynamics.
    • The air conditioner uses a diffuser to distribute cool air evenly.
Synonyms