ETYM Latin navalis, from navis ship: cf. French naval. Related to Nave of a church.
Connected with or belonging to or used in a navy.
ETYM French océan, Latin oceanus, Greek okeanos ocean, in Homer, the great river supposed to encompass the earth.
1. A large body of water constituting a principal part of the hydrosphere.
2. Anything apparently limitless in quantity or volume; SYN. sea.
Great mass of salt water. Strictly speaking three oceans exist —the Atlantic, Indian, and Pacific—to which the Arctic is often added. They cover approximately 70% or 363,000,000 sq km/140,000,000 sq mi of the total surface area of the Earth. Water levels recorded in the world's oceans have shown an increase of 10–15 cm/4–6 in over the past 100 years.
Depth (average) 3,660 m/12,000 ft, but shallow ledges 180 m/600 ft run out from the continents, beyond which the continental slope reaches down to the abyssal zone, the largest area, ranging from 2,000–6,000 m/6,500–19,500 ft. Only the deep-sea trenches go deeper, the deepest recorded being 11,034 m/36,201 ft (by the Vityaz, ussr) in the Mariana Trench of the W Pacific 1957.
Features deep trenches (off E and se Asia, and western South America), volcanic belts (in the W Pacific and E Indian Ocean), and ocean ridges (in the mid-Atlantic, E Pacific, and Indian Ocean).
Temperature varies on the surface with latitude (-2şC/28.4şF to +29şC/84.2şF); decreases rapidly to 370 m/1,200 ft, then more slowly to 2,200 m/7,200 ft; and hardly at all beyond that.
Water contents salinity averages about 3%; minerals commercially extracted include bromine, magnesium, potassium, salt; those potentially recoverable include aluminum, calcium, copper, gold, manganese, silver.
Oceans have always been used as a dumping area for human waste, but as the quantity of waste increases, and land areas for dumping it diminish, the problem is exacerbated. Today ocean pollutants include airborne emissions from land (33% by weight of total marine pollution); oil from both shipping and land-based sources; toxins from industrial, agricultural, and domestic uses; sewage; sediments from mining, forestry, and farming; plastic litter; and radioactive isotopes. Thermal pollution by cooling water from power plants or other industry is also a problem, killing coral and other temperature-sensitive sedentary species.
ETYM Old Eng. see, as. sae; akin to Dutch zee, os. and Old High Germ. sęo, German see, OFries. se, Dan. sö, Swed. sjö, Icel. saer, Goth. saiws, and perhaps to Latin saevus fierce, savage.
1. A division of an ocean or a large body of salt water partially enclosed by land.
2. Turbulent water with swells of considerable size.
Ein stehendes Gewässer, das mit dem Meer nicht unmittelbar verbunden ist. Man unterscheidet Süßwasser- u. Salz-S. (Salzgehalt über 5‰).
1. A body of (usually fresh) water surrounded by land.
2. A purplish red pigment prepared from lac or cochineal.
3. Any of numerous bright translucent organic pigments.
Body of still water lying in depressed ground without direct communication with the sea. Lakes are common in formerly glaciated regions, along the courses of slow rivers, and in low land near the sea. The main classifications are by origin: glacial lakes, formed by glacial scouring; barrier lakes, formed by landslides and glacial moraines; crater lakes, found in volcanoes; and tectonic lakes, occurring in natural fissures.
Crater lakes form in the calderas of extinct volcanoes, for example Crater Lake, Oregon. Subsidence of the roofs of limestone caves in karst landscape exposes the subterranean stream network and provides a cavity in which a lake can develop. Tectonic lakes form during tectonic movement, as when a rift valley is formed. Lake Tanganyika was created in conjunction with the East African rift valley. Glaciers produce several distinct types of lake, such as the lochs of Scotland and the Great Lakes of North America.
Lakes are mainly freshwater, but salt and bitter lakes are found in areas of low annual rainfall and little surface runoff, so that the rate of evaporation exceeds the rate of inflow, allowing mineral salts to accumulate. The Dead Sea has a salinity of about 250 parts per 1,000 and the Great Salt Lake, Utah, about 220 parts per 1,000. Salinity can also be caused by volcanic gases or fluids, for example Lake Natron, Tanzania.
In the 20th century large artificial lakes have been created in connection with hydroelectric and other works. Some lakes have become polluted as a result of human activity. Sometimes eutrophication (a state of overnourishment) occurs, when agricultural fertilizers leaching into lakes cause an explosion of aquatic life, which then depletes the lake's oxygen supply until it is no longer able to support life.
1. Scottish and Irish words for lake; SYN. lough.
2. A long narrow inlet of the sea in Scotland (especially when it is nearly landlocked) and in Ireland; SYN. lough.