knock vs knocker

knock and knocker both are nouns.

Word	Noun	Adjective	Verb	Adverb
knock	Yes	No	Yes	No
knocker	Yes	No	No	No

knock (noun)	knocker (noun)
the act of hitting vigorously	a device (usually metal and ornamental) attached by a hinge to a door
negative criticism	either of two soft fleshy milk-secreting glandular organs on the chest of a woman
a vigorous blow	one who disparages or belittles the worth of something
the sound of knocking (as on a door or in an engine or bearing)	a person who knocks (as seeking to gain admittance)
a bad experience	(Yiddish) a big shot who knows it and acts that way; a boastful immoderate person

knock (verb)	knocker (verb)
find fault with; express criticism of; point out real or perceived flaws
knock against with force or violence
rap with the knuckles
deliver a sharp blow or push
make light, repeated taps on a surface
sound like a car engine that is firing too early