the.com/planetesimal

means A small solid body of rock, ice, or dust formed in the early solar system's protoplanetary disk, the kind that collides and clumps with others to eventually build planets.

from Coined in English astrophysics by analogy with 'infinitesimal' — taking 'planet' and grafting on that same tiny-and-incremental suffix, '-esimal,' used in math terms like infinitesimal to mean a vanishingly small unit within a larger scale. The word itself enacts its own meaning: a small fragment of 'planet' that's part of a vast accumulating process.