Nonrenewable energy refers to energy sources that come from fossil fuels such as coal, gas, and oil, which cannot be replenished over time. There are a number of synonyms for nonrenewable energy that can be used interchangeably, including fossil fuels, finite resources, and depletable energy sources. These synonyms are important because it is critical to raise awareness about the impact that nonrenewable energy sources have on the environment, including air and water pollution, and climate change. The widespread use of nonrenewable energy sources is unsustainable in the long-term, as these resources will eventually run out, making it essential to develop more sustainable and renewable sources of energy.