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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

"Turn around, turn around, turn around!" he shouts at the top of his lungs to encourage them to run in circles.

From Barron's • Jun. 30, 2026

The other strand follows his grocery run in Bakersfield.

From Salon • Jun. 30, 2026

Hamilton made a mistake on his first run in Q3, locking a brake at Turn Three, and had to abort the lap.

From BBC • Jun. 27, 2026

Stocks limped to the end of a five-day slump on Friday, a run in which even blowout earnings from chip maker Micron couldn’t build any traction in major indexes.

From The Wall Street Journal • Jun. 26, 2026

I guess rhymes must run in the family.

From "Rump: The (Fairly) True Story of Rumpelstilskin" by Liesl Shurtliff