(A Glossary) Here are some common terms relevant to home ownership. For a complete list, visit "http://www.nachi.org"www.nachi.org and click on Glossary. An abbreviation for Air Conditioner, Air Conditioning, or Alternating Current. An opening in the wall or ceiling near the fixture that allows access for servicing the plumbing/electrical system. The area between the sidewalk and the street that leads to a driveway ortransition from the street as you approach a driveway.