planetoid, old use minor planet [noun] [C] - one of many rocky objects, varying in width from over 900 kilometres to less than one kilometre, which circle the sun. Most are situated between the orbits (= paths around the sun) of the planets Mars and JupiterAsteroids are also known as 'minor planets'.
ASTEROID
Meaning of ASTEROID in English
Cambridge English vocab. Кембриджский английский словарь. 2012