reducer

/rɪˈduːsər/
noun
  1. A device or substance that reduces something, such as pressure, size, or flow.
    • A pressure reducer is essential for safe gas cylinder operation.
    • This chemical acts as a reducer in the reaction, removing oxygen from the compound.
    • The plumber installed a reducer to connect the large pipe to the smaller one.
  2. A person or thing that makes something smaller, less, or simpler.
    • She is known as a cost reducer in the company, always finding ways to save money.
    • The new software is a great reducer of file sizes, saving storage space.
    • Adding this ingredient is a natural fat reducer in recipes.