A radio source (RS, and within radio astronomy, sometimes just the word, source) is an object, or a location in the celestial sphere from which radio is detected. The term radio source avoids interpretation (i.e., any declaration what kind of object is producing the radio), though it is often used even when a certain type of source is assumed. The Sun, Jupiter, and the galactic center are sources. Some other source types:
In the case of galaxies, the word "source" may be used to indicate the location within the galaxy or adjacent to the galaxy (as in the case of radio stemming from jets) from which the radio signal is observed.
The terms extended source versus point source or unresolved source indicate whether it is resolved. The term giant radio source (GRS) may refer to the physical size of the source, which generally assumes at least some notion of the distance, or possibly may be based on the angular area across the celestial sphere.
The term GHz-peaked spectrum (GPS) refers to some extragalactic sources showing a peak in the gigahertz (microwave) range. They are presumed to be a type of active galactic nucleus.
Terms microwave source and X-ray source are also used, in analogous manner.