N-COUNT(指代不知其名或不愿用确切词汇或固有名称指称的人或物)那人,那东西,某某 You refer to something or someone as thingummy ,thingummyjig or thingummybob when you do not know or cannot be bothered to use the proper word or name for them.
I once bought a thingummy out of one of those catalogues...