Added 10 October 2026 planetology noun Categories: Obscure Words noun ! Definition from Wiktionary (CC BY-SA). More about planetology at Wordnik → Where our words come from → The study of planets, planetary systems and the solar system. Related Words: planetophysicsplanetographeratmospherologyexoplanetologyastrogeologyhetegonyprotistologyprotozoologygeographyastrophilosophy Back to today's word