The term Planetoid is used in more than one sense, generally meaning an object like a planet but small. The term Minor Planet is used in pretty much the same way. The term Moon is used instead for objects orbiting planets. Often the term is specifically meant not to include Comets. The term Asteroid is used similarly, but sometimes used specifically for planetoids within the Asteroid Belt, inside Jupiter's orbit.
Planetoid detection around other stars has not been achieved. However, the term is sometimes used in discussion of planet systems (and their formation) around other stars.