Home › Words › R › reactionlessnessreactionlessnessreactionlessness · noun — absence of reaction.Definition from Wiktionary (CC BY-SA 3.0).Among words judged in Lexicurio's Arena, reactionlessness ranks #16,851 of 42,854 for Qualifying.EtymologyFrom reactionless + -ness.nounAbsence of reaction.Definitions & examples from Wiktionary (CC BY-SA 3.0).