planetesimal hypothesis planetesimal • planet gear · · · Info · Definitions · Characters · · planetesimal hypothesis · · Text Common · · Latin · · Scripts 23 · · Length 9 · · Syllables Definitions · · · (noun) (cosmology) the theory that the solar system was formed by the gravitational accumulation of planetesimals. Synonyms: planetesimal hypothesis. · · Noun Definition 1 Characters · · space U+0020 a latin small letter a U+0061 e latin small letter e U+0065 h latin small letter h U+0068 i latin small letter i U+0069 l latin small letter l U+006C m latin small letter m U+006D n latin small letter n U+006E o latin small letter o U+006F p latin small letter p U+0070 s latin small letter s U+0073 t latin small letter t U+0074 y latin small letter y U+0079