Extrasolar is a term used to describe celestial bodies that orbit a star outside our solar system. It is a scientific term and has various synonyms, including exoplanet, exoworld, exo-planet, extrasolar planet, and extrasolar world. These synonyms are used interchangeably but, exoplanet is the most commonly used among them. Exoplanet is derived from the words "extraordinary planet," reflecting their rare occurrence and uniqueness. Apart from exoplanets, there are also exomoons, brown dwarfs, and other space entities that can be classified as extrasolar. As a result, the science of researching these celestial bodies outside our solar system is called extrasolar planetary science.