Wiktionary
n. (context US slang English) An object, especially a gadget, whose name the speaker currently cannot recall.
Usage examples of "dealy".
After they left, she found a spent cartridge bearing the name "Mannlicher-Carcanno," the rifle that the Warren Commission claimed Oswald used to perform his historic feat of marksmanship in Dealy Plaza.
Stirring up the locals with a score would be completely counterproductive, especially if she stirred them up enough to catch her with spice or dealies or whatever the kid was carrying that was making him so nervous.
Standing in my front yard, I could see it hanging over the sea like a light bulb – not a hundred watter, like the sun, but maybe one of those twenty-five dealies you put in those swivel-neck desk lamps.
Both have these pinch-on plastic picture dealies that say California Bell.