# protoplanet

> English word · Noun

## Definitions
1. An astronomical object, approximately the size of the Moon, formed from the mutual gravitational attraction of planetesimals; they are thought to collide with each other and slowly form planets

## Etymology
From proto- + planet.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/protoplanet