Home › Words › P › pachyostosispachyostosispachyostosis means A thickening of the bones of the ribs and vertebrae.Among words judged in Lexicurio's Arena, pachyostosis ranks #16,734 of 42,752 for Qualifying.EtymologyFrom pachy- + ostosis.nounA thickening of the bones of the ribs and vertebrae.Definitions & examples from Wiktionary (CC BY-SA 3.0).