Definitions

1. noun

A small celestial body that orbits a star, especially one that is too small to be a full-fledged planet, such as an asteroid or a Kuiper belt object.

“The planetoid was discovered in the outer reaches of the solar system.”

2. noun

A hypothetical or proposed planet, especially one that is not yet confirmed by observation or discovery.

“Scientists have proposed a new planetoid in the distant reaches of the galaxy.”