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• run-in
  run-in

  noun

  a quarrel; argument.
• run in
  run in

  verb

  to run (an engine) gently, usually for a specified period when it is new, in order that the running surfaces may become polished

run-in

American  

[ruhn-in] / ˈrʌnˌɪn /

noun

1. a quarrel; argument.

2. Printing. matter that is added to a text, especially without indenting for a new paragraph.

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adjective

1. Printing. added to a text without indenting.

run in British  

verb

1. to run (an engine) gently, usually for a specified period when it is new, in order that the running surfaces may become polished

2. (tr) to insert or include

3. (intr) (of an aircraft) to approach a point or target

4. informal (tr) to take into custody; arrest

   he was run in for assault

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noun

1. informal an argument or quarrel

   he had a run-in with the boss yesterday

2. an approach to the end of an event, etc

   the run-in to the championship

3. printing matter inserted in an existing paragraph

run in Idioms  

1. Insert or include something extra, as in Can you run this map in with the text? [Early 1800s]

2. Also, run on . In printing, make a solid body of text without a paragraph or other break, as in The quotation should be run in rather than set as a paragraph .

3. Also, run someone in . Take someone into custody, as in The police were going to run him in, but he got away . [ Slang ; mid-1800s]

4. Visit someone briefly, as in If I have time, I'll run in to see Aunt Mary . [Second half of 1800s]

5. Break something or someone in, as in Let's run in the new model on a short flight . [Early 1900s] Also see run into .

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Etymology

Origin of run-in

First recorded in 1900–05; noun, adj. use of verb phrase run in

Explanation

A run-in is a confrontation or an argument. Peaceful protests go more smoothly when protestors avoid run-ins with the police. If you get in a fight with your brother about how he never loads the dishwasher, you can call that a run-in. A more serious kind of run-in might be a shoplifter's run-in with a store security guard or a basketball player's angry run-in with a referee that gets him benched for the rest of the season. Before 1905, run-in meant an instance of actually running somewhere.

Example Sentences

The other strand follows his grocery run in Bakersfield.

From Salon • Jun. 30, 2026

Trainer Kyrraley Woodhouse, who started camel racing professionally in 2013, said most of his camels had been taken from the wild to run in the Marree event, which drew more than a dozen competitors.

From Barron's • Jun. 28, 2026

In the first half, this pattern occurred but it was Kane making the run in behind and, for all of his quality, he is not the speediest.

From BBC • Jun. 28, 2026

“He never hit a home run in his life.”

From Los Angeles Times • Jun. 26, 2026

“Wait a second, okay? I need to run in there.”

From "What If It's Us" by Becky Albertalli and Adam Silvera