Home › Words › S › soapnutsoapnutsoapnut means the drupe of Sapindus plants, containing saponins, which are a natural surfactant.Among words judged in Lexicurio's Arena, soapnut ranks #3,412 of 42,747 for Qualifying.EtymologyFrom soap + nut.nounThe drupe of Sapindus plants, containing saponins, which are a natural surfactant.e.g.“Soapnuts are the dried fruit of a tree called Sapindus mukorossi (Chinese Soapberry) and contain saponin, a natural surfactant that foams just like soap.” — 2015, Beth Terry, Plastic-Free: How I Kicked the Plastic Habit and How You Can Too, Simon and Schuster, →ISBN:Definitions & examples from Wiktionary (CC BY-SA 3.0).