| Term | Definition |
| Hydrologic cycle | The cycle through which water in the hydrosphere moves; includes such processes as evaporation, precipitation, and surface and groundwater runoff |
| Evaporation | The process of changing from a liquid to a gas |
| Condensation | the process of changing from a gaseous to a liquid or solid state |
| Precipitation | water that falls to Earth's surface as rain, snow, sleet, or hail |
| Infiltration | the slow passage of a liquid through a filtering medium |
| Surface runoff | water that flows over land until it reaches lakes, rivers, or other areas |
| Transpiration | the emission of water vapor from the leaves of plants |
| Groundwater | water held in rocks and soil below the surface |