Final answer:
A nonrenewable resource is a natural resource that exists in a fixed amount and cannot be replenished quickly. Examples include fossil fuels like petroleum, coal, and natural gas. Once these resources are used up, they cannot be replaced within human timescales.
Step-by-step explanation:
A nonrenewable resource is a natural resource that exists in a fixed amount and cannot be replenished at all or cannot be replenished quickly enough to keep pace with human use of the resource. Examples of nonrenewable resources include fossil fuels like petroleum, coal, and natural gas, which took millions of years to form and are being consumed by humans at a faster rate than they can be replaced by nature. Once these resources are used up, they cannot be replaced within human timescales, usually taking millions of years to replenish.