Thingumys

Part of speech: noun

Definitions

1. A placeholder noun used in place of the name of a thing that the speaker cannot recall or does not know
2. A stand-in word for an object, device or item whose proper name has slipped someone's mind
3. A vague label applied to any gadget or object when its correct name is unknown or unimportant

Etymology: "Thingumys" is a plural form, so the real work is in the root. It is the plural of "thingumy," a playful noun meaning an object whose name you cannot recall, which is itself a shortening of "thingumajig" (also "thingumabob" or "thingummy"). The "-jig" and "-bob" endings are the nonsense-syllable additions that English speakers have tacked onto "thing" for centuries to stand in for a name they have forgotten. The "thing" at the core is an Old English word, "þing," meaning an assembly or matter for discussion before it meant a physical object. The sense of an object you cannot name grew out of that general, almost empty, meaning of "thing," which could refer to nearly anything. "Thingumajig" appears in print in the 18th century, and the shorter "thingumy" follows in the 19th.