| Term | Definition |
| groundwater | water stored in soil and rock beneath Earth's surface |
| pollutants | substances that cause pollution |
| pesticides | chemicals used to kill crop-destroying organisms |
| sediments | particles of rock and sand |
| sewage | water and human waste washed down drains |
| emissions | pollutants that are released into the air |
| photochemical smog | thick brownish haze produced when certain pollutants react with sunlight |
| ozone | produced when sunlight reacts with oxygen |
| temperature inversion | layer of warm air prevents air from rising |
| acid rain | precipitation that is more acidic than normal |