rugged vs knockabout

rugged is not a noun while knockabout is a noun.

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

rugged (noun)	knockabout (noun)
	a sloop with a simplified rig and no bowsprit

rugged (adjective)	knockabout (adjective)
sturdy and strong in constitution or construction; enduring	suitable for rough use
having long narrow shallow depressions (as grooves or wrinkles) in the surface	full of rough and exuberant animal spirits
very difficult; severely testing stamina or resolution
topographically very uneven