Breadcrumb Home > Thesaurus Cite Synonyms of planetesimal Find synonyms for: Noun1. planetesimal, celestial body, heavenly bodyusage: one of many small solid celestial bodies thought to have existed at an early stage in the development of the solar systemWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.See also: planetesimal (Dictionary) Related Content Daily Word Quiz: polemic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language Synonyms Index