Definition of "aeration"

aeration

/ɛːˈreɪʃ(ə)n/

noun
countable and uncountable, plural aerations
1. The process by which air is circulated through or mixed with a substance such as soil or a liquid.
  Quotations
  The Mekydro transmission employs a single converter and a four-speed mechanical gearbox, which has the advantage of cheapness and simplicity for the same number of gear changes, and does away with the necessity for constantly emptying and filling converters, which tends to harm the oil by aeration.
  1960 January, “The Swindon Type "4" diesel-hydraulic units”, in Trains Illustrated, pages 41–42
2. By extension, a process in which other gases (such as carbon dioxide or nitrogen or argon) are circulated through or mixed with a substance (usually liquid), sometimes with the consequence of increasing the transfer of air into the same liquid at the surface due to the induced circulation.