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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
Synonyms

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.


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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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 .


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.

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

In his 2025 memoir, “Truly,” Richie recounted a chance run-in with the comedian George Burns at the Polo Lounge.

From The Wall Street Journal Sep. 16, 2026

Trump and Cohen broke the ice during a “brief yet significant” run-in at one of Trump’s golf clubs last summer, the New York Times reported.

From Slate Aug. 24, 2026

The LP opens with “Casablanca,” in which she recounts a run-in with the Grateful Dead’s Bob Weir in New Orleans in the late ’80s.

From Los Angeles Times Aug. 4, 2026

After a rough start, including a run-in with an irritating policeman, she lands at the home of a baker, Osono, who gives her a place to stay in exchange for labor and her delivery services.

From Salon Jul. 30, 2026

A long time ago Mr. MacMahon had a bad run-in with a horse hisself.

From "Elijah of Buxton" by Christopher Paul Curtis

Also see: The 10-year Treasury is having its worst run in over 100 years.

From MarketWatch Sep. 19, 2026

Barrio Athletics had planned to start and end their run in tiny Leimert Plaza Park while also setting up a DJ and smoothie stand there.

From Los Angeles Times Sep. 18, 2026

Beesley, a documentary filmmaker and avid catfish noodler, had taken a shine to Walters during Mudcats’ run in 2012 and 2013.

From Slate Sep. 17, 2026

The bill initially looked like a home run in the House, too.

From The Wall Street Journal Sep. 16, 2026

Dr. Howard explained that a “genetic factor” means that vitiligo can sometimes run in families.

From "How to Disappear Completely" by Ali Standish

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