glacier

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A huge mass of ice slowly flowing over a land mass, formed from compacted snow in an area where snow accumulation exceeds melting and sublimation.

Century Dictionary and Cyclopedia

1. n. The form in which the snow, falling on the higher parts of those mountain-ranges which are above the snow-line, finds its way down into the valleys. Under suitable climatic conditions, the snow which thus falls does not all disappear by evaporation, or melt at once and run off in the form of water, but becomes gradually converted into ice, and moves slowly down the mountain-slope in the depressions or valleys until it reaches a point where the mean temperature has so far risen that evaporation and melting counterbalance the supply from above. Here the glacier ends, and a stream of water begins, which is often the head of some large river, as the Gangootri glacier of the Ganges, or the Rhone glacier of the river of that name. The snow of the glacier is not transformed into ice at once, but passes through the intermediate stage of névé (German firn). (See firn.) Several subordinate glaciers often combine to form one large one, a result dependent on the topography of that part of the mountain-range in which the glacier takes its rise. The great glaciers, those of the first order, as the Gorner and the Aletsch glaciers in Switzerland, begin in large amphitheaters (cirques), where a considerable number of affluents are forced by the topographical conditions to unite in forming one great glacier. The ice-stream of the longest glacier in the Swiss Alps, the Gross Aletsch, was in 1880 10¼ miles in length; some in the Himalayas are four times as long. From the cliffs which overhang the glacier is always being detached, by frost and aërial erosion, more or less detritus, which is carried downward on the ice as it moves, and finally dumped at the terminus of the ice-mass. Such accumulations of debris are called moraines, and are very conspicuous on many glaciers. (See moraine.) The former greater extension of glaciers over certain regions has been, and still is, a subject of much discussion among geologists. See the glacial epoch (under glacial) and ice.—
2. n. A vessel for holding ice and cooling wine.

Wiktionary

1. n. A large body of ice which flows under its own mass, usually downhill.

GNU Webster's 1913

1. n. An immense field or stream of ice, formed in the region of perpetual snow, and moving slowly down a mountain slope or valley, as in the Alps, or over an extended area, as in Greenland.

WordNet 3.0

1. n. a slowly moving mass of ice