run-in
Americannoun
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a quarrel; argument.
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Printing. matter that is added to a text, especially without indenting for a new paragraph.
adjective
verb
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to run (an engine) gently, usually for a specified period when it is new, in order that the running surfaces may become polished
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(tr) to insert or include
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(intr) (of an aircraft) to approach a point or target
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informal (tr) to take into custody; arrest
he was run in for assault
noun
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informal an argument or quarrel
he had a run-in with the boss yesterday
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an approach to the end of an event, etc
the run-in to the championship
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printing matter inserted in an existing paragraph
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Insert or include something extra, as in Can you run this map in with the text? [Early 1800s]
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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 .
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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]
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Visit someone briefly, as in If I have time, I'll run in to see Aunt Mary . [Second half of 1800s]
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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.
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.
He was flanked by two classic Stormtroopers, who had different dialogue in each showing — one time critiquing Black Spire Outpost and later talking of a run-in with a Jedi.
From Los Angeles Times • Apr. 29, 2026
O'Reilly and Doku were beginning to form an impressive and rotating partnership that Guardiola would rely on for the run-in.
From BBC • Apr. 25, 2026
Former Celtic striker Chris Sutton predicts the outcome of all 380 Premier League games for BBC Sport - so he seemed an obvious choice to have his say on the title run-in.
From BBC • Apr. 24, 2026
Although Manchester City have a tougher run-in than Arsenal on paper, their knowhow in terms of getting the job done during a tight race will prove crucial.
From BBC • Apr. 24, 2026
Yesterday Mother and I had another run-in and she really kicked up a fuss.
From "The Diary of a Young Girl" by Anne Frank
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Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.