leaded vs antiknock

leaded is not a noun while antiknock is a noun.

Word	Noun	Adjective	Verb	Adverb
leaded	No	Yes	No	No
antiknock	Yes	Yes	No	No

leaded (noun)	antiknock (noun)
	any of various compounds that are added to gasoline to reduce engine knocking

leaded (adjective)	antiknock (adjective)
treated or mixed with lead	suppressing or eliminating engine knock in combustion engines
(of panes of glass) fixed in place by means of thin strips of lead
having thin strips of lead between the lines of type