antiknock vs leaded

antiknock is a noun but leaded is not a noun.

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

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

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