| Term | Definition |
| glacier | a large mass of moving ice |
| snowline | elevation above which ice and snow remain throughout the year |
| snowfield | an almost motionless, permanent mass of ice and snow on the ground |
| firn | grainy ice formed through cycles of melting and re-freezing |
| alpine glacier | a narrow, wedge-shaped glacier that forms in muntainous regions |
| continental glacier | a massive sheet of ice that may cover millions of square kilometers |
| ice sheet | another name for a continental glacier |
| crevasse | a large crack or fissure that results from ice movement |
| ice shelf | an ice sheet that hangs over an ocean |
| iceberg | large blocks of ice which have broken away from a glacier or ice shelf, onto the ocean |
| ice age | a long period of climactic cooling during which the continents are glaciated repeatedly |
| glacial period | a period of cooler climate during which glaciers advance |
| interglacial period | a period of warmer climate during which glaciers retreat |
| Milankovitch Theory | theory that cyclical changes in Earth's orbig and the tilt of Earth's axis over thousands of years cause climactic changes |
