knocker

noun ! Definition from WordNet 3.1, Princeton University. Pronunciation from Wiktionary, via Kaikki.org. More about knocker at Wordnik → Where our words come from →

1. (Yiddish) a big shot who knows it and acts that way; a boastful immoderate person.
2. A person who knocks (as seeking to gain admittance).

   open the door and see who the knocker is

3. One who disparages or belittles the worth of something.