set on

attack someone, or order dogs or others to attack them

C1

What does "set on sb" mean?

To 'set on' someone means to attack them, either physically or by directing others — such as dogs, guards, or hired muscle — to do the attacking for you. The classic construction involves a person in a position of power sending an aggressive force against a target: a landowner setting dogs on trespassers, or a crime boss setting thugs on a rival. It can also describe a sudden group ambush, where several people attack one person, often without warning. The passive form — 'he was set on' — is extremely common, especially in news reports and narrative prose, and shifts the focus to the victim rather than who gave the order. Figuratively, 'set on' extends to sending lawyers, debt collectors, or any kind of enforcer after someone, preserving the sense of deliberately directing an aggressive force.

Examples

How to use it

set + agent + on + target

The most common construction: a person directs an aggressive force (dogs, thugs, guards) against a specific target.

The factory owner threatened to set his guard dogs on anyone who approached the fence.

set on + target (group attack)

Used when a group attacks a victim directly, without a separate directing agent — common in crime and narrative contexts.

A group of men set on the journalist outside the conference centre.

be set on + by + attacker(s)

The passive is very natural and common, especially when the victim is the focus and the attacker may or may not be named.

She was set on by two strangers as she crossed the car park alone.

set + agent + on + pronoun

Pronouns work very naturally as the target in this construction, especially in spoken or informal contexts.

If you keep trespassing, I'll set the dogs on you.

threaten to set + agent + on + target

Frequently appears in a threat structure, where the attack is a warning rather than something already carried out.

The corporation threatened to set its lawyers on any publication that ran the story.

Common Collocations

set the dogs on someoneset thugs on someonebe set on by a gangset a mob on someoneset guards on someone

Common Mistakes

Confusing the 'attack' and 'determined' senses

The phrase 'be set on' looks identical whether it means 'attack' or 'be determined', but the grammar is different. In the attack sense, 'set on' is an active verb with a human or animal target; in the determined sense, it follows 'be' and is followed by a gerund or noun, never a person as target.

✗ She was set on by winning the contract. (mixing the two senses)
✓ She was set on winning the contract. (determined) / She was set on by a rival's enforcers. (attacked)
Dropping the target entirely

'Set on' in this sense always requires a target — the person or group being attacked. Using it without an object produces an ungrammatical sentence.

✗ The mob arrived and just set on.
✓ The mob arrived and set on the security guards.
Inserting the target between 'set' and 'on'

When directing an agent (like dogs or thugs), the agent goes between 'set' and 'on', but the target always follows 'on'. Placing the victim before 'on' breaks the construction.

✗ He set the rival on his dogs.
✓ He set his dogs on the rival.

Usage

This phrasal verb is neutral in register and appears in both spoken and written English. 'Set the dogs on someone' is also used figuratively, meaning to send lawyers, debt collectors, or aggressive people after someone.

Frequently Asked Questions

Is 'set on' the same as 'set upon'?

'Set upon' is a near-identical variant with the same attack meaning, but it sounds slightly more formal or literary. You can generally use them interchangeably — 'he was set upon by thieves' and 'he was set on by thieves' both work — though 'set upon' appears more often in written or historical prose.

Can 'set on' be used figuratively, not just for physical attacks?

Yes, and this is quite common. 'Set the dogs on someone' is frequently used to mean sending lawyers, debt collectors, investigators, or other aggressive parties after a person. The key is that the meaning of deliberately directing a threatening force at a target is preserved, even if no one is actually being punched.

Does 'set on' always involve someone giving the order to attack, or can it describe a spontaneous attack?

Both are possible. The 'directing others' construction ('set the dogs on him') always implies someone giving an order. But 'set on' can also describe a spontaneous group ambush ('they set on him in the alley'), where the emphasis is on the sudden, coordinated nature of the attack rather than someone commanding it.

Can I use 'set on' in the present continuous — for example, 'they are setting on him'?

This form is grammatically possible but sounds awkward in most contexts. The simple past, past perfect, or passive forms are far more natural. The present continuous might work in a dramatic or live-narration context, but for general use, stick to 'they set on him' or 'he was being set on by the guards'.

What kinds of 'agents' can be used in the 'set [agent] on [target]' construction?

The most common are dogs, guards, thugs, a mob, or hired men — anything that functions as an aggressive, directed force. In figurative use, lawyers, debt collectors, and enforcers also appear frequently. The agent should always be something with the capacity to threaten or harm the target.

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