In vertebrates such as mammals the abdomen (belly) constitutes the part of the body between the thorax (chest) and pelvis. The region enclosed by the abdomen is termed the abdominal cavity. In arthropods it is the most distal section of the body which lies behind the thorax or cephalothorax.


An acetate (IUPAC name: ethanoate) is either a salt or an ester of acetic acid. Its formula is written both as CH3CO2− and C2H3O2−.

Chemists abbreviate acetate as OAc− and AcO−. Thus HOAc is the abbreviation for acetic acid, NaOAc for sodium acetate, and EtOAc for ethyl acetate Acetate is a common anion in biology.


Acetone is the organic compound with the formula OC(CH3)2. This colorless, mobile, flammable liquid is the simplest example of the ketones. Owing to the fact that acetone is miscible with water it serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory.



An acid (from the Latin acidus meaning sour) is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion activity greater than in pure water, i.e. a pH less than 7.0.

Acid/base systems are different from redox reactions in that there is no change in oxidation state. Acids can occur in solid, liquid or gaseous form, depending on the temperature. They can exist as pure substances or in solution.

Chemicals or substances having the property of an acid are said to be acidic.


To transform in acid


Quality of something that is acid.



The acorn, or oak nut, is the nut of the oaks and their close relatives.

It usually contains a single seed (rarely two seeds), enclosed in a tough, leathery shell, and borne in a cup-shaped cupule. Acorns vary from 1–6 cm long and 0.8–4 cm broad. Acorns take between about 6 or 24 months (depending on the species) to mature.


Bacon is a cured meat prepared from a pig. It is first cured in a brine or in a dry packing, both containing large amounts of salt; the result is fresh bacon (also green bacon). Fresh bacon may then be further dried for weeks or months (usually in cold air), boiled, or smoked. Fresh and dried bacon must be cooked before eating. Boiled bacon is ready to eat, as is some smoked bacon, but either may be cooked further before eating.

Bacon is prepared from several different cuts of meat. In the United States, it is almost always prepared from pork belly. Elsewhere, it is more often made from side and back cuts, and bacon made from bellies is referred to as “streaky”, “fatty”, or “American style”. The side cut has more meat and less fat than the belly. Bacon may be prepared from either of two distinct back cuts: fatback, which is almost pure fat, and pork loin, which is very lean. Bacon-cured pork loin is known as back bacon.

Bacon may be eaten smoked, boiled, fried, baked, or grilled, or used as a minor ingredient to flavor dishes. Bacon is also used for barding and larding roasts, especially game birds. The word is derived from the Old High German bacho, meaning “buttock”, “ham” or “side of bacon”, and cognate with the Old French bacon.

In continental Europe, this part of the pig is usually not smoked like bacon is in the United States; it is used primarily in cubes (lardons) as a cooking ingredient, valued both as a source of fat and for its flavor. In Italy, this is called pancetta and is usually cooked in small cubes or served uncooked and thinly sliced as part of an antipasto.

Meat from other animals, such as beef, lamb, chicken, goat, or turkey, may also be cut, cured, or otherwise prepared to resemble bacon, and may even be referred to as “bacon”. Such use is common in areas with significant Jewish and Muslim populations. The USDA defines bacon as “the cured belly of a swine carcass”; other cuts and characteristics must be separately qualified (e.g., “smoked pork loin bacon”). For safety, bacon must be treated for trichinella, a parasitic roundworm which can be destroyed by heating, freezing, drying, or smoking.

Bacon is distinguished from salt pork and ham by differences in the brine (or dry packing). Bacon brine has added ingredients, most notably sodium nitrite, and occasionally sodium nitrate or saltpeter, are added to cure the meat; sodium ascorbate or erythorbate are added to accelerate curing and stabilize color. Flavorings such as brown sugar or maple are used for some products. If used, sodium polyphosphates are added to improve sliceability and reduce spattering when the bacon is pan fried. Today, a brine for ham, but not bacon, includes a large amount of sugar. Historically, “ham” and “bacon” referred to different cuts of meat that were brined or packed identically, often together in the same barrel.