from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Informal A thingamajig.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Placeholder word for a thing or person nonspecific, unknown or forgotten
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. something unspecified whose name is either forgotten or not known
Alteration of thingumbob : obsolete thingum (from thing) + bob2.(American Heritage® Dictionary of the English Language, Fourth Edition)