ETYM Old Eng. barre, French barre, from Late Lat. barra, W. bar the branch of a tree, bar, baren branch, Gael. and Irish barra bar.
1. A rigid piece of metal.
2. A rod of metal used to obstruct openings.
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3. (Usually in the plural) Jail.
4. A counter where one can purchase food or drink.
5. A submerged (or partly submerged) ridge in a river or along a shore.
6. (Law) A railing that encloses the part of the courtroom where the the judges and lawyers sit and the case is tried.
7. A unit of pressure equal to a million dynes per square centimeter.
A unit of pressure equal to 0.99 atmospheres or 14.233 psi.
ETYM French, from barrer to bar, from barre bar.
The rapid and continuous delivery of linguistic communication (spoken or written); SYN. outpouring, onslaught.
ETYM Old Eng. barrere, barere, French barričre, from barre bar. Related to Bar.
1. A structure or object that impedes free movement.
2. Any condition that makes it difficult to make progress or to achieve an objective; SYN. roadblock.
3. Anything serving to maintain separation by obstructing vision or access.
Causeway.
Ravine; trench; gully.
(Homonym: damn).
1. A barrier constructed to contain the flow or water or to keep out the sea; SYN. dike, dyke, levee.
2. Female parent of an animal especially domestic livestock.
Structure built to hold back water in order to prevent flooding, to provide water for irrigation and storage, and to provide hydroelectric power. The biggest dams are of the earth- and rock-fill type, also called embankment dams. Early dams in Britain, built before about 1800, had a core made from puddled clay (clay which has been mixed with water to make it impermeable). Such dams are generally built on broad valley sites. Deep, narrow gorges dictate a concrete dam, where the strength of reinforced concrete can withstand the water pressures involved.
A valuable development in arid regions, as in parts of Brazil, is the underground dam, where water is stored on a solid rock base, with a wall to ground level, so avoiding rapid evaporation. Many concrete dams are triangular in cross section, with their vertical face pointing upstream. Their sheer weight holds them in position, and they are called gravity dams. They are no longer favored for very large dams, however, as they are expensive and time-consuming to build. Other concrete dams are built in the shape of an arch, with the curve facing upstream: the arch dam derives its strength from the arch shape, just as an arch bridge does, and has been widely used in the 20th century. They require less construction material than other dams but are the strongest type.
Buttress dams are used when economy of construction is important or foundation conditions preclude any other type. The upstream portion of a buttress dam may comprise series of cantilevers, slabs, arches or domes supported from the back by a line of buttresses. They are usually made from reinforced and prestressed concrete.
Earth dams have a watertight core wall, formerly made of puddle clay but nowadays constructed of concrete. Their construction is very economical even for very large structures. Rock-fill dams are a variant of the earth dam in which dumped rock takes the place of compacted earth fill.
Major dams include: Rogun (Tajikistan), the world's highest at 335 m/1,099 ft; New Cornelia Tailings (US), the world's biggest in volume, 209 million cu m/7.4 billion cu ft; Owen Falls (Uganda), the world's largest reservoir capacity, 204.8 billion cu m/7.2 trillion cu ft; and Itaipu (Brazil/Paraguay), the world's most powerful, producing 12,700 megawatts of electricity. The Three Gorges Dam on the Chang Jiang was officially inaugurated December 1994.
Although dams can service huge irrigation schemes and are a reliable and cheap source of power, they cause many environmental problems such as the forcible removal of local communities, waterlogging and salinization of land in the area, and loss of habitat. For example, the world's biggest hydroelectric dam and irrigation project which is currently under construction on the Narmada river, central India, has attracted huge protests as it will displace up to a million people and submerge large areas of forest and farmland. Similarly, the Kansa dam in Zimbabwe flooded habitat used by the rhinoceros, one of the world's most endangered mammals.
There is also controversy as to the effectiveness of large dams as the reservoirs tend to fill with silt from upstream. This leads to a gradual reduction in reservoir depth and hence the volume of water held back by the dam which in turn reduces the power delivered by the hydroelectric turbines.
ETYM Old Eng. dic, dike, diche, ditch, AS. dîc dike, ditch.
(Homonym: dyke).
1. A ditch; a channel for water made by digging.
2. An embankment to prevent flooding; a levee.
3. A wall of turf or stone.
A long artificial mound of stone or earth; built to hold back water or to support a road or as protection.
ETYM Cf. French escarpement.
A steep artificial slope in front of a fortification; SYN. escarp, scarp, protective embankment.
Large ridge created by the erosion of dipping sedimentary rocks. It has one steep side (scarp) and one gently sloping side (dip). Escarpments are common features of chalk landscapes, such as the Chiltern Hills and the North Downs in England. Certain features are associated with chalk escarpments, including dry valleys (formed on the dip slope), combes (steep-sided valleys on the scarp slope), and springs.
1. A gate for shutting out, admitting, or releasing a body of water; sluice
2. Something serving to restrain an outburst
ETYM French jetée a pier, a jetty, a causeway. Related to Jet a shooting forth, and cf. Jutty.
1. A wharf or pier extending from the shore.
2. A structure of wood or stone extended into the sea to influence the current or tide, or to protect a harbor.
(Homonym: loch).
1. A fastener fitted to a door or drawer to keep it firmly closed.
2. A device incorporated into the ignition switch to prevent the use of a vehicle by persons who do not have the key; SYN. ignition lock.
3. A mechanism that detonates the charge of a gun.
4. A strand or cluster of hair; SYN. curl, ringlet, whorl.
5. Any wrestling hold in which some part of the opponent's body is twisted or pressured.
6. Section of canal that can be closed to control the water level; used to raise or lower vessels that pass through it; SYN. lock chamber.
Construction installed in waterways to allow boats or ships to travel from one level to another. The earliest form, the flash lock, was first seen in the East in 1st-century-AD China and in the West in 11th-century Holland. By this method barriers temporarily dammed a river and when removed allowed the flash flood to propel the waiting boat through any obstacle. This was followed in 12th-century China and 14th-century Holland by the pound lock. In this system the lock has gates at each end. Boats enter through one gate when the levels are the same both outside and inside. Water is then allowed in (or out of) the lock until the level rises (or falls) to the new level outside the other gate.
Locks are important to shipping where canals link oceans of differing levels, such as the Panama Canal, or where falls or rapids are replaced by these adjustable water “steps”.
A dam to make a millpond to provide power for a water mill.
Pigmented area on the skin. See naevus.
Person working subversively within an organization. The term has come to be used broadly for someone who gives out (“leaks”) secret information in the public interest; it originally meant a person who spends several years working for a government department or a company with the intention of passing secrets to an enemy or a rival.1. Small velvety-furred burrowing mammal having small eyes and fossorial forefeet.
2. A small congenital pigmented spot on the skin.
3. (Mexican) Spicy sauce often containing chocolate.
A wall or embankment to protect the shore from erosion or to act as a breakwater. SYN. sea-wall
ETYM Old Fren. escluse, French écluse, Late Lat. exclusa, sclusa, from Latin excludere, exclusum, to shut out: cf. Dutch sluis sluice, from the Old French. Related to Exclude.
Carries a rapid flow of water controlled by a sluicegate; SYN. sluiceway, penstock.
A gate in a sluice that can control the flow of water; SYN. floodgate.
(Homonym: ware, where).
1. Impairment resulting from long use.
2. The act of wearing; SYN. wearing.
ETYM Old Eng. wer, AS. wer; akin to German wehr, AS. werian to defend, protect, hinder, German wehren, Goth. warjan; and perhaps to Eng. wary; or cf. Skr. vor to check, hinder. Cf. Garret.
(Homonym: we're).
1. A fence or wattle built across a stream to catch or retain fish.
2. A low dam built across a stream to raise its level or divert its flow.
Low wall built across a river to raise the water level. The oldest surviving weir in England is at Chester, across the river Dee, dating from around 1100.