Alterations refer to changes (AA's) made by a customer or author to a typeset manuscript. These are not due to typographer's error, and thus are chargeable to the customer.

The airport is a place used by planes for takeoff and landing.

Airfield is referring to:

1. An area of open level ground equipped with hangars and runways for aircraft;

Aeroplane is an English term which is also known as airplane in American English, which refers to a mechanically, power-driven heavier-than-air flying machine that has fixed wings deriving its lift in flight chiefly from aerodynamic reactions on surfaces which remain fixed under given conditions of flight.

Aeration is a term in aquaculture systems that refers to the mechanical mixing of air and water; this generally refers to a process by which gases contained in air are transferred across the air-liquid interface (in contrast with the transfer of oxygen alone).

Advanced material relates to the development of materials, including semiconductor materials, optical fiber cable, and videodisks, that enhance the application of other advanced technologies.

Adulterated food refers to impure, unsafe, or unwholesome; food however, the Federal Food, Drug, and Cosmetic Act, the Federal Meat Inspection Act, the Poultry Products Inspection Act, and the Egg Products Inspection Act has made another definition of the term adulteres which will be applied to the foods each of these laws regulates.

Acidified food pertains to low-acid foods that have their pH lowered to 4.6 or less by the addition of acids or acid foods. Example are the pickles or pickled vegetables and fruits.