API = American Petroleum Institute.
The American Petroleum Institute (API) is the national trade association that represents all aspects of America’s oil and natural gas industry.
Also refers to:
- API gravity is a measure of how heavy or light a petroleum liquid is compared to water. If its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks.
- API unit, unit of radioactivity used for measuring natural gamma rays in the ground. The radioactivity of a typical shale is 100 API units.