antiknocking vs antiknock

antiknocking is not a noun while antiknock is a noun.

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

As adjectives, antiknocking and antiknock are synonyms defined as:

antiknocking and antiknock: suppressing or eliminating engine knock in combustion engines

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

antiknocking (adjective)	antiknock (adjective)
suppressing or eliminating engine knock in combustion engines	suppressing or eliminating engine knock in combustion engines