Home › Words › S › subcrustsubcrustsubcrust means synonym of undercrust (“layer under the crust of a planet etc.”).Among words judged in Lexicurio's Arena, subcrust ranks #16,730 of 42,747 for Qualifying.EtymologySub- + crustnounSynonym of undercrust (“layer under the crust of a planet etc.”).Definitions & examples from Wiktionary (CC BY-SA 3.0).