Quick answer: “Keep someone at arm's length” means to avoid becoming too closely involved with someone, maintaining emotional or professional distance.
Keep someone at arm's length — To avoid becoming too closely involved with someone; to maintain deliberate emotional or professional distance rather than letting them get close.
Meaning
When you “keep someone at arm's length”, you deliberately avoid becoming emotionally close, personally involved, or fully trusting with them. The idiom is often used to describe caution after being hurt, a desire to protect privacy, or a professional need to remain neutral and impartial. It suggests a controlled, intentional distance rather than accidental coldness.
The expression appears often in discussions of personal relationships, workplace dynamics, and public life — for example, a public figure keeping the press at arm's length, or someone keeping a difficult family member at arm's length after a falling out. It is neutral in tone and used comfortably in both spoken and written English.
Origin & Usage Note
The idiom draws on the simple, concrete image of holding something at the full length of an outstretched arm — close enough to control, but far enough to avoid direct contact. This physical picture was extended figuratively to describe emotional or social distance, likely because the image of literally pushing something away captures the deliberate, controlled nature of the behaviour so clearly. The phrase also survives in business and legal English, where an “arm's length transaction” describes a deal between independent parties with no personal connection.
Example Sentences
| Sentence | Context |
|---|---|
| After the argument, she started keeping her old friend at arm's length. | Personal relationship; distance after conflict |
| The CEO prefers to keep journalists at arm's length during ongoing negotiations. | Public relations and media management |
| He's always kept his in-laws at arm's length, though he's polite whenever they meet. | Family relationships |
| Managers should keep an arm's length relationship with staff when handling complaints. | Workplace neutrality and impartiality |
| She kept new colleagues at arm's length until she felt she could trust them. | Building trust gradually at work |
How to Use It
The idiom is most often used with the verb “keep”, as in “keep someone at arm's length”, and always requires the possessive apostrophe in “arm's”. It works well in both spoken conversation and professional or business writing, including its adjectival use as in “an arm's length relationship” or “an arm's length transaction”. It should not be used to describe simple physical distance without an emotional or relational meaning.
Common Mistakes
Mistakes to Avoid
She kept him at arms length after the disagreement.
She kept him at arm's length after the disagreement. — The correct form includes the possessive apostrophe: “arm's length”, not “arms length”.
He stood at arm's length from the door to open it.
He stood an arm's length from the door to open it. — When describing literal physical distance, the idiom loses its figurative force; it is best reserved for relationships, not physical positioning.
They keep at arm's length with each other.
They keep each other at arm's length. — The idiom needs a direct object; “keep someone at arm's length” is the correct structure, not “keep at arm's length with someone”.
Similar Idioms
Practise This Idiom
Practice English Idioms
Use these exercises to master idioms in context:
Want to understand the grammar behind this? Explore our Grammar guides.
Quick Check: Keep someone at arm's length
2 questions — test what you just learned.
1. What does “keep someone at arm's length” mean?
2. Complete the sentence: “After the argument, she started keeping her old friend _____.”
Frequently Asked Questions
What does “keep someone at arm's length” mean?
“Keep someone at arm's length” means to avoid becoming too closely involved with someone, deliberately maintaining emotional, social, or professional distance rather than letting them get close to you.
Where does the expression “at arm's length” come from?
The idiom draws on the simple physical image of holding something or someone at the distance of an outstretched arm, far enough away to prevent close contact. This literal image was extended figuratively over time to describe emotional or professional distance rather than a physical gap.
Can you give an example of “keep someone at arm's length” in a sentence?
Here is an example: “After the argument, she started keeping her old friend at arm's length.” The sentence shows the speaker deliberately reducing closeness with someone following a conflict.
Is “keep someone at arm's length” formal or informal?
The idiom is neutral in register. It is common in everyday conversation about relationships, and it also appears in business and legal writing, where “an arm's length transaction” describes a deal between independent, unrelated parties.
What CEFR level is “keep someone at arm's length”?
This idiom is typically encountered at B2 level. It requires learners to understand a figurative use of physical distance to describe emotional or social relationships, a concept usually mastered at the upper-intermediate stage.
What are common mistakes with “keep someone at arm's length”?
A common mistake is forgetting the possessive apostrophe, writing “at arms length” instead of “at arm's length”. Another error is using the wrong verb, such as “hold at arm's length” when referring to a relationship rather than a physical object; while acceptable, “keep” is the most natural choice for relationships. Learners should also avoid implying literal physical distance when the meaning is emotional or professional.
What is the difference between “at arm's length” and “keep your distance”?
“Keep your distance” is a more general instruction that can apply to physical space, safety, or relationships. “At arm's length” specifically evokes controlled, deliberate emotional or professional distance from a particular person, often implying wariness or a wish to avoid becoming too involved.
Is “arm's length” used in business contexts?
Yes. In business and legal English, an “arm's length transaction” or “arm's length relationship” describes a deal or relationship between two independent parties acting in their own interests, without personal connection or undue influence. This usage is common in contracts, financial reporting, and tax law.
How do I practise idioms like “keep someone at arm's length”?
LexFizz's Flip Tiles and Flash Cards exercises are excellent for practising English idioms in context. Try writing your own example sentences and look for the idiom in articles about relationships, workplace dynamics, or business deals.
Is “at arm's length” used in both British and American English?
Yes. “At arm's length” is used identically in both British and American English, in both personal and business contexts, and it is widely understood across all major varieties of English.