thingumEtymologyPerhaps originally from the gradational compound thingum-thangum (based on thing) with the same terminal syllable as in crinkum-crankum, harum-scarum, trinkum-trankum.thingum means synonym of thingummy. Lexicurio rates it Sui generis — a strength score of 92 out of 100.nounSynonym of thingummy.