aerator aerator /ˈɛəreɪtər/

noun

1. () An apparatus for exposing something to the air (as sewage)  ( aerator )
   an apparatus for exposing something to the air (as sewage)
     The lawn aerator helps improve the health of the grass by allowing air and water to penetrate the soil.
   The lawn aerator helps improve the health of the grass by allowing air and water to penetrate the soil.