crampon

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

• noun A hinged pair of curved iron bars for raising heavy objects, such as stones or timber.
• noun A spiked iron or steel framework attached to the bottom of a shoe or boot to prevent slipping when walking or climbing on ice and snow.

from The Century Dictionary.

• noun An iron instrument fastened to the shoes of a storming party, to assist them in climbing a rampart.
• noun An apparatus used in the raising of heavy weights, as timber or stones, and consisting of two hooked pieces of iron hinged together somewhat like double calipers.
• noun In botany, an adventitious root which serves as a fulcrum or support, as in the ivy.

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

• noun (Bot.) An aërial rootlet for support in climbing, as of ivy.
• noun a device with pointed metal projections worn over the shoes to provide traction when walking over ice, or in mountaineering; -- usually used in the plural.
• noun same as crampoon.

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

• noun An attachment to a shoe or boot that provides traction by means of spikes. Used for climbing or walking on slippery surfaces, especially ice.
• noun botany An aerial rootlet for support in climbing, as of ivy.

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

• noun an iron spike attached to the shoe to prevent slipping on ice when walking or climbing
• noun a hinged pair of curved iron bars; used to raise heavy objects