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knock against (someone or something)
1. noun A valid flaw or criticism of someone or something. A big knock against these media streaming services is the fact that any piece of media you enjoy can be pulled from their servers at the drop of a hat. He was forgiving to the point of naïveté, one of the few knocks against an otherwise beloved figure within the community.
2. verb To bump into or jostle against someone or something. Whenever the train lurched to the side, the man next to me would knock against me. As the tide came in, debris from the accident knocked against the boats anchored in the harbor.
3. verb To bump or strike something against someone or something else. In this usage, a noun or pronoun is used between "knock" and "against." The woman kept knocking her bags against other passengers as she made her way down the aisle. Please stop knocking your feet against the legs of the table like that.
4. verb To cause someone or something to bump into or collide with someone or something else very swiftly and sharply. In this usage, a noun or pronoun is used between "knock" and "against." The force of the impact knocked us all against the wall. He stumbled backward into the bookshelf, knocking it against the wall.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
knock (up) against someone or something
to bump against someone or something. The loose shutter knocked up against the side of the house. The large branch knocked against the garage in the storm.
knock something against something
to strike something against something. He knocked a chair against the table and tipped both pieces of furniture over. A chair was knocked against the table, upsetting a vase.
knock against someone or something
to bump against someone or something. Mickey knocked against Mary and said he was sorry. I didn't mean to knock against your sore knee.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.