cobwebby vs cobweb

cobwebby is not a noun while cobweb is a noun.

Word	Noun	Adjective	Verb	Adverb
cobwebby	No	Yes	No	No
cobweb	Yes	No	No	No

cobwebby (noun)	cobweb (noun)
	a dense elaborate spider web that is more efficient than the orb web
	filaments from a web that was spun by a spider
	a fabric so delicate and transparent as to resemble a web of a spider

cobwebby (adjective)	cobweb (adjective)
covered with cobwebs
so thin as to transmit light