1 B2 idiomatic informal
(British, informal) To arrest someone and take them to a police station
"The officer threatened to run him in if he didn't calm down."
separable
run in
B2 informal separable transitive
To arrest someone and take them to a police station, or to operate a new engine gently at first to break it in
In plain English
When police take you to the station, or when you drive a new car gently at first so the engine works well
What does "run in" mean?
2 meanings, ordered from most common to least. Color-coded by CEFR level.
2 C1 neutral
To operate a new engine or machine gently and carefully at first so it functions correctly over time
"You should run in a new car by keeping the revs low for the first thousand miles."
separable
Literal vs figurative
Words literally mean
To run into a place — the police sense relates to bringing someone into the station
Actually means
When police take you to the station, or when you drive a new car gently at first so the engine works well
Usage tip
The arrest sense is informal British English. The engine sense ('running in' a car) is becoming less common as modern engines require less careful breaking in.
Words that pair with "run in"
Natural word combinations native speakers use most often.
police engine car suspect arrest gearbox
How to conjugate "run in"
The five tense forms you'll use most often.
Base
run in
I/you/we/they
3rd person
runs in
he/she/it
Past simple
ran in
yesterday
Past participle
run in
have + pp
-ing form
running in
continuous
Hear "run in" in the wild
Listen to native speakers using "run in" in real YouTube videos — click a clip to watch it on Looplines.
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