Aerator 
Mechanism, which mixes air into water, soil, sewage, etc. Alternately, the part on the end of a sink spout which mixes air with the water to reduce splattering. 

Aerial Photograph 
Photographs taken from a plane or other high place. see also Aerial Photos.

Aerial Survey 
Survey made by using aerial photography from either a plane or other high place. 

Aerial Photos 
Photographs of land areas and buildings taken by cameras mounted in airplanes or satellites. Aerial photographs are used by developers or builders for the use of prospective buyers. They are also used by civil engineers, geologists, geographers, archaeologists, etc. see also Aerial Photograph.

Aerodynamics 
Study of the effects of air and other gases on bodies where relative motion exists between them. 

Aerosol 
Mixture in a pressurized container, which has small particles of solid or liquid, suspended in gas and is dispensed through a special nozzle that atomizes it into a spray. 

Aesthetic 
Beauty. That which is pleasing to the eye. 

Aesthetic Value 
Property value, which is increased due to its intrinsic artistic, beautiful and favored location. 

Affiant 
Someone who makes a sworn statement. 

Affidavit 
A written statement or declaration, which is made under oath before a licensed individual, such as a notary public. 

Affidavit of Title 
Document in which the seller (the affiant) identifies himself/herself and swears to his/her marital status and that he/she is in possession of the property and certifies that, since the date of the examination of title, there have been no judgments, divorces unrecorded deeds, unpaid repairs, bankruptcies or defects in title which are known to him/her. 

Affirm 
To confirm, ratify, verify and accept a transaction, which can be cancelled. 

Affirmation 
An alternative to an oath, which can be used on people whose religious beliefs will not allow an oath. 

Affix 
To fasten or attach. 

Afforestation 
Creating a forest cover on land area not previously forested to increase the aesthetic value of the land and to prevent erosion and improving the environment. 

A-Frame 
Outer shape of a structure which has steeply sloped roofs and is in the shape of an A, hence the name. 

After-acquired Title 
Doctrine by which the title of real estate, previously unsuccessfully transferred because of lack of possession by grantor, automatically passes to the buyer upon acquisition by the grantor and is based on the acquisition of title by estoppel. 

After-completion Costs 
Expenditures incurred after the completion of a building. 

Aftergrowth 
The second growth of timber from areas where trees have been harvested previously. 

After-Sheathing Window 
A window that is installed after the sheathing is installed. This is more difficult than installing the before sheathing window. With an after sheathing window, the carpenter must nail through the casing and sheathing into the jack studs; one nails through a wood lip, directly into the studs, on a before sheathing type. 

After-tax Cash Flow 
Cash flow (from income producing property), which is reduced by income taxes resulting from the property's income. 

After-tax Equity Yield 
Net return rate, after deduction of interest costs and taxes, on an equity investment in real estate. 

After-tax Rate of Return 
Rate of return on investment once income taxes are deducted.

Agar 
Gelatinous substance used as paper sizing and as an emulsifier for adhesives. It is harvested from seaweed. 

Agata 
Stained glass that has a mottled rose and white color to it. 

Age-life Depreciation 
Depreciation method based on the projected useful life of the property, allowing for normal wear and tear. 

Aged Mediterranean Texture 
Stucco, which has been textured with areas of, flattened blotches that are troweled on a furrowed surface. 

Agency 
The relationship between two people or entities where one is a principal and the other is an agent representing the principal in activities with other parties, such as a real estate agent buying or selling for a client. 

Agency Closing
The use of a Title company or another firm to complete a loan. 

Agency Disclosure 
Law requiring disclosure from real estate agents as to which party, buyer or seller, they represent. Laws vary in different states. 

Agenda 
List of items that need to be considered or accomplished. 

Agent 
Anyone who has the authority to act on the behalf of another, representing the business interests of that person. 

Aggregate 
Sand or stone component used as a filler in the making of concrete, which consists of Portland cement, water and the aggregate, which makes up 75 percent of the bulk. Aggregate ranges in size from sand, which is a fine aggregate to stone up to 2 ½" wide and is a coarse aggregate, depending on the strength needed. Although an aggregate does not add much strength to the mix, the wrong size stone or one of poor quality can weaken the mix. Alternately, the whole of something. 

Aggregate, Coarse 
Aggregate made up of coarse material, 1/4 inch and larger. 

AGI
see Adjusted Gross Income.

Aging List 
Summary of accounts receivable, along with the time those bills have been owed and which are past due. 

Agitator 
Apparatus used for shaking or stirring to mix. 

Agreement 
An understanding between two or more people. A contract. 

Agreed Boundary 
A compromise reached by two property owners to resolve a dispute over borders. 

Agreement of Sale 
A document detailing the terms and sale price of a transaction, along with a description of the property and any time limits. A contract obligates the buyer to buy and the seller to sell and is normally accompanied by a deposit from the buyer. 

Agricultural Property 
Property zoned for use in farming, including the raising of crops and livestock. 

Agricultural Use Value 
Determination of value of agricultural land by taking into consideration the amount of arable land (property not disrupted by trees or overgrowth or untillable terrain), its proximity to an adequate water supply and the climatic location. 

AIA
see American Institute of Architects

Aiguille 
An instrument for drilling holes in rocks, stone or masonry. 

Air Acetylene Welding (ACW) 
Process for welding, either with or without a filler metal, which uses a heat source that is produced by the combustion of acetylene with air. 

Air Brick 
Hollow bricks, which are open at both, end and used to permit air to pass through a wall and are placed at different locations as air vents. 

Air Rights 
Rights to use the open air space above a street, railroad line, or other property. Sometimes used to allow construction of billboards or other signage. Air rights may also allow the construction of entire buildings, such as when a development is constructed over an existing highway. 

Airbrush 
Apparatus that applies paint by the use of compressed air and a fine nozzle. In this manner, application is able to be controlled to cover only a small area. 

Air Carbon Arc Cutting (AAC) 
Cutting process that melts metal with an electric arc from a carbon electrode and then removes it with a jet of air. 

Air Chamber 
Capped piece of pipe, close to a plumbing fixture, which is partially filled with air. Also called air cushions they are designed to absorb shock from abrupt water stoppage, which creates a noise known as water hammer. 

Air Change 
The exchange of air that is in a confined space with fresh air. 

Air Cleaner 
Filtering device, which removes particles from the air, usually at the intake of an engine or mechanical device. 

Air Conditioner 
System of circulating air and controlling its temperature and humidity, along with removing airborne impurities. 

Air Conditioning 
Process of controlling temperature, humidity and movement in a confided space. 

Air Content 
Volume of air in concrete, cement or mortar. Air Cooled Reduction in the temperature, which is caused by the transfer of heat to air as it circulates. 

Air Cooled Cooling System Condenser 
Finned, tube-type condenser through whose tubes a refrigerant is circulated, giving heat to air passing over the outside of the finned tubes, cooling the refrigerant. 

Air Cushion Tank 
An expansion tank. Closed tank in a hot water system providing space for the water expansion in the system as it is heated. Tank contains both water and air and as the water expands, the air in the tank is compressed. 

Air Dried Lumber 
Lumber that is dried by being exposed to natural air rather than with the aid of heating devices. 

Air Driven Nailer 
Machine using compressed air to drive nails and is also referred to as a pneumatic nailer. 

Air Duct 
Used for directing the passage of air through buildings, these large thin-walled conduits are usually made of sheet metal or fiberglass. 

AIREA
see American Institute of Real Estate Appraisers.

Air Ejector 
To maintain a vacuum and improve the operating efficiency of a condenser, an air ejector is used to remove non-condensable gasses from steam condensers. 

Air-entrained Concrete 
Concrete that has been altered chemically, with an additive, to disperse air bubbles through the mix. A yard of air-entrained concrete may contain over three trillion bubbles. This mix is easier to work than standard concrete and stands up well in cold weather, resisting salts better than other concrete. While it is good for pouring in cold weather because the bubbles allow the concrete to expand and contract more readily, it is not as strong as regular concrete. Also referred to as Aerated Concrete. 

Air Entrapment 
Defect caused by air bubbled which have formed on a new paint surface. 

Air Feed 
Powdered material, which is to be thermally deposited on a surface, is carried by an air stream and sprayed on the surface to be coated by means of this disbursing system. When heat conditions are appropriate, the material bonds to the surface. 

Airfoil 
Device, which is shaped to provide a lifting, force when moved through an air current. 

Airfoil Fan 
Fan with blades with an airfoil cross section. 

Air Gap
Vertical, unobstructed distance, between the flood level in a plumbing fixture and the lowest water supply inlet, such as the distance between the rim of the tub and the faucet. 

Air Gun 
Compressed air powered nozzle, it is used for the spray application of paint, etc. 

Air Hammer 
A pneumatic nailer, essentially a hammer driven by compressed air. 

Air Handling Unit 
Unit designed to move air and sometimes change the temperature, through the use of a fan system. These units, used in air distribution systems, circulate air throughout buildings by means of a series of ducts. 

Air Pocket 
Dead air spaces in concrete, which are also known as a void, are usually one millimeter, with entrained pockets being smaller. 

Airless Sprayer 
Spray gun that uses pressure from a mechanical pump to pressurize the liquid or spin it from a wheel to apply paint or other liquid finishes. 

Air Lock 
Blockage in the flow of liquid, especially on the suction side of the pump, which is caused by a gas bubble trapped in the line. Also called a vapor lock, a gas-tight chamber with an entrance and exit that is used as a passage into another space. 

Air Pocket 
Dead air spaces in concrete, which are also known as a void, are usually one millimeter, with entrained pockets being smaller. 

Air Relief Valve 
Valve that is used to vent air out of a water system. 

Air Space or Lot
Designated area over a piece of property. Alternately, a space between walls or wall surfaces that is created as part of the architectural design. 

Air Tight 
Structure or container constructed to contain gas pressure. 

Air Vent 
Valve in a water system that automatically vents trapped air from the system. 

Aisle 
Pathway through sections of a building or room, such as between sections of seats in a theater.