gulf

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

• noun A large area of a sea or ocean partially enclosed by land, especially a long landlocked portion of sea opening through a strait.
• noun A deep, wide chasm; an abyss.
• noun A wide gap, as in understanding.
• noun Something, such as a whirlpool, that draws down or engulfs.
• transitive verb To engulf.

from The Century Dictionary.

• To swallow; engulf; cast down, as into a gulf.
• In the University of Cambridge, to place in the gulf, or among those students who have barely escaped being plucked in their final examination.
• To flow like the waters of a gulf.
• noun A large tract of water extending from the ocean or a sea into the land, following an indentation of the coastline: as, the Gulf of Mexico; the Gulf of Venice.
• noun An abyss; a chasm; a deep place in the earth: as, the gulf of Avernus.
• noun Something that engulfs or swallows, as the gullet, or a whirlpool; figuratively, misfortune.
• noun A wide interval, as in station, education, and the like: as, the gulf that separates the higher and lower classes.
• noun In Cambridge University, England, the place at the bottom of the list of passes where the names of those who have barely escaped being plucked in examination are written. These names are separated by a line from those of the students who have passed creditably.
• noun In mining, a large deposit of ore in a lode.

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

• noun A hollow place in the earth; an abyss; a deep chasm or basin
• noun obsolete That which swallows; the gullet.
• noun That which swallows irretrievably; a whirlpool; a sucking eddy.
• noun (Geog.) A portion of an ocean or sea extending into the land; a partially land-locked sea.
• noun (Mining) A large deposit of ore in a lode.
• noun (Geog.) the warm ocean current of the North Atlantic.
• noun (Bot.) a branching seaweed (Sargassum bacciferum, or sea grape), having numerous berrylike air vessels, -- found in the Gulf Stream, in the Sargasso Sea, and elsewhere.

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

• noun A hollow place in the earth; an abyss; a deep chasm or basin.
• noun obsolete That which swallows; the gullet.
• noun That which swallows irretrievably; a whirlpool; a sucking eddy.
• noun geography A portion of an ocean or sea extending into the land; a partially landlocked sea; as, the Gulf of Mexico or Persian Gulf.
• noun mining A large deposit of ore in a lode.
• noun A difference, especially a large difference, between groups

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

• noun an arm of a sea or ocean partly enclosed by land; larger than a bay
• noun a deep wide chasm
• noun an unbridgeable disparity (as from a failure of understanding)