Planetoid

 were astronomical bodies smaller than actual planets, closer in size to asteroids.

Major Nadina Haunt led a group of soldiers on a training mission on a planetoid near Vertigan Majoris. (PROSE: Ten Little Aliens)

Voga was a planetoid that got caught by Jupiter's gravity and became one of its moons. (TV: Revenge of the Cybermen)

A segment of the Key to Time was hidden as a lake on the surface of the planetoid Erratoon. (AUDIO: The Prisoner's Dilemma)

The Makers created a futuristic city on a planetoid in the late 30th century. ([[PROSE: The Space Age)

An Earth colony was established on a planetoid sometime before 2479, which they named New Memphis. (PROSE: Judgement of the Judoon)

House was a sentient planetoid which existed in a bubble universe. (TV: The Doctor's Wife)

Bernice Summerfield visited the Drome, which was described as planetoid Hollywood. (AUDIO: The Worst Thing in the World)