Thingamybob

Part of speech: noun

Definitions

1. An object or gadget whose actual name you don't know or can't remember at the moment
2. A thing for which you lack the proper name, whether because you've forgotten it or never knew it
3. Any object or device that you cannot or do not wish to name specifically

Etymology: "Thingamybob" is a spelling variant of "thingamabob," a word for an object whose name you cannot recall or do not know. Its roots lie in "thing" plus "thingum," an older word that was itself a playful extension of "thing." The earliest recorded use of the form "thingumbobs" dates to 1751, and the word has since shifted through a series of spellings as speakers reshaped it. The "bob" element is the most puzzling part. It appears to be a nonsense-style addition, the kind of sound that English speakers tacked onto words for comic or affectionate effect, and it gave the word its cheerful, slightly bouncy rhythm.

Synonyms: thingamajig, whatchamacallit, gadget, contraption