All spiders create their webs through a liquid secretion that hardens in the air.
These webs are nearly invisible, especially to the insects they trap.
In modern language, the spider’s web becomes a cobweb only after it collects dust and becomes visible, so the webs are different in name only.
The word cob came from writings as early as the thirteenth century and had evolved from coppe, an early word for spider.
The word coppe and cob dont seem to match. In my Websters Dictionary under cob, one meaning says ” a rounded mass, lump, or heap. This would make since because it is like a webbie heap of dust. A mass of dusty webs. (It was just an idea.)