A radiometer is a device that measures radiant flux, or the amount of energy transmitted through electromagnetic waves. There are several synonyms for radiometer depending on the context in which it is used. For instance, some of the alternatives to radiometer used in science and engineering include spectrometer, photometer, and luminometer. In the medical field, radiometer is often interchangeably used with blood gas analyzer. The term pyranometer is used to mean a specific type of radiometer that measures solar radiation. In summary, while radiometer is a common term, several other words can be used to convey the same meaning depending on the setting.