rugged vs ruggedness

rugged is not a noun while ruggedness is a noun.

Word	Noun	Adjective	Verb	Adverb
rugged	No	Yes	No	No
ruggedness	Yes	No	No	No

rugged (noun)	ruggedness (noun)
	the property of being big and strong
	the quality of being topologically uneven
	the quality of being difficult to do

rugged (adjective)	ruggedness (adjective)
sturdy and strong in constitution or construction; enduring
having long narrow shallow depressions (as grooves or wrinkles) in the surface
very difficult; severely testing stamina or resolution
topographically very uneven