What is planetsimal?

Answer 1

Planetesimal: a small, irregularly shaped body formed irregular by colliding matter

Answer 2

A planetesimal is a small body that could have eventually come together to form a planet during the early stages of the formation of the solar system. These objects are composed of rock, dust, and other materials, and they range in size from a few kilometers to several hundred kilometers in diameter. Planetesimals played a crucial role in the accretion process that led to the formation of planets.