ocean

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The entire body of salt water that covers more than 70 percent of the earth's surface.
• noun Any of the principal divisions of the ocean, including the Atlantic, Pacific, Indian, Arctic, and Southern Oceans.
• noun A great expanse or amount.

from The Century Dictionary.

• noun The body of water which envelops the earth, and covers almost three fourths of its surface with a mean depth — as nearly as can be estimated at the present time — of less than 12,500 feet.
• noun Something likened to the ocean; also, a great quantity: as, an ocean of trouble.
• Of or pertaining to the main or great sea.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Of or pertaining to the main or great sea
• noun The whole body of salt water which covers more than three fifths of the surface of the globe; -- called also the sea, or great sea.
• noun One of the large bodies of water into which the great ocean is regarded as divided, as the Atlantic, Pacific, Indian, Arctic and Antarctic oceans.
• noun An immense expanse; any vast space or quantity without apparent limits

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun countable One of the five large bodies of water separating the continents.
• noun uncountable Water belonging to an ocean.
• noun figuratively An immense expanse; any vast space or quantity without apparent limits.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun anything apparently limitless in quantity or volume
• noun a large body of water constituting a principal part of the hydrosphere