cheat on

2 meanings

Meanings
  1. 1 have a secret romantic or sexual relationship with someone else while in a relationship B2
  2. 2 break the rules in a test or exam to get a better result B2
1 cheat on sb

have a secret romantic or sexual relationship with someone else while in a relationship

B2

What does "cheat on" mean in this sense?

To cheat on someone means to have a romantic or sexual relationship with another person while you are already in a committed relationship. It describes a betrayal of trust within a partnership — whether that involves a boyfriend, girlfriend, spouse, or long-term partner. The phrase is most commonly heard in everyday conversation, advice columns, and dramatic storylines, and it carries a strong emotional weight because of the deception involved. A useful pattern to know is 'cheat on X with Y', which names both the person who was betrayed and the third party. While it overlaps with 'be unfaithful to', 'cheat on' is far more common in spoken English and informal writing.

Examples

How to use it

cheat on + person

The core pattern — the person being betrayed always follows the full phrase 'cheat on', never between the two words.

Everyone was shocked to hear that he had cheated on his partner of seven years.

cheat on + person + with + person

Use this extended pattern when you want to name the third party involved in the betrayal.

It turned out she had been cheating on her boyfriend with someone from her old job.

have been cheating on + person + for + time expression

The present perfect continuous is especially common here because it emphasises that the betrayal was ongoing over a period of time.

He admitted he had been cheating on her for almost two years.

be cheated on (passive)

The passive form is natural when the focus is on the person who experienced the betrayal rather than the person who caused it.

She only found out she had been cheated on when a friend told her the truth.

catch / find out / suspect + someone + cheating on + person

These verbs of discovery frequently appear with 'cheating on' to describe the moment or process of uncovering the betrayal.

His sister suspected he was cheating on his wife long before anyone else did.

Common Collocations

cheat on a partnercheat on a husband/wifecheat on a boyfriend/girlfriendbeen cheating on someone for monthscatch someone cheating on youfind out someone cheated on you

Common Mistakes

Trying to separate the verb

'Cheat on' is inseparable, so the object must always come after the full phrase. Placing the object between 'cheat' and 'on' is incorrect in any situation.

✗ He cheated her on while they were living together.
✓ He cheated on her while they were living together.
Confusing the two meanings of 'cheat on'

'Cheat on' can also mean to use dishonest methods in an exam or test. The key is the object: if it's a person in a romantic relationship, it means infidelity; if it's an exam or assignment, it means academic dishonesty. These are two completely different meanings, so context matters.

Using 'cheat' alone when the partner needs to be named

While saying 'he was cheating' can work when the context is already clear, you need 'cheat on + person' if you want to specify who was betrayed. Leaving out 'on' before the person's name produces an unnatural sentence.

✗ She cheated her husband the whole time they were married.
✓ She cheated on her husband the whole time they were married.

Usage

This is a neutral, everyday expression used in both British and American English. Note that 'cheat on' can also mean to cheat in an exam, so context is important.

2 cheat on sth

break the rules in a test or exam to get a better result

B2

Sense 2: What does "cheat on sth" mean?

To cheat on a test or exam means to use dishonest methods during an assessment — for example, copying someone else's answers, smuggling in hidden notes, or using an unauthorised device. This sense of the phrasal verb is specifically about academic dishonesty and always appears with an assessment-related word after 'on', such as an exam, test, quiz, assignment, or homework. It is a neutral phrase that works equally well in casual conversation between students and in formal school reports or disciplinary documents. One thing that makes this phrasal verb particularly useful is how naturally it fits with verbs of consequence: learners will frequently encounter it after 'caught', 'accused of', 'expelled for', and 'suspected of'. Note that the same phrasal verb has a completely different meaning when the object is a person — context always makes it clear which sense is intended.

Examples

How to use it

cheat on + assessment noun

The standard pattern — the object after 'on' must be an assessment-related noun such as exam, test, quiz, or assignment.

Two students were caught cheating on the final exam and had their grades cancelled.

caught / accused of / expelled for + cheating on + assessment noun

The gerund form 'cheating on' is especially common after verbs and phrases that describe being discovered or disciplined.

She was accused of cheating on her midterm after the invigilator noticed her looking at her phone.

be tempted to cheat on + assessment noun

Used to describe the impulse or pressure a student feels to act dishonestly, without necessarily doing so.

He admitted he had been tempted to cheat on the standardised test but decided it wasn't worth the risk.

cheat on + assessment noun + by + -ing

Use this pattern to specify the method of cheating.

She cheated on the quiz by writing answers on a small piece of paper hidden in her sleeve.

Common Collocations

cheat on an examcheat on a testcheat on homeworkcaught cheating onexpelled for cheating oncheat on a quiz

Common Mistakes

Using 'cheat at' instead of 'cheat on'

'Cheat at' is used with games and sports, not with exams or assessments. When talking about academic dishonesty, always use 'cheat on'.

✗ He was suspended for cheating at the entrance exam.
✓ He was suspended for cheating on the entrance exam.
Trying to separate the phrasal verb

'Cheat on' is inseparable — the object always comes after 'on'. Never place the exam or test between 'cheat' and 'on'.

✗ She cheated the test on to get a better grade.
✓ She cheated on the test to get a better grade.
Using the passive with the exam as subject

Because the exam is a prepositional object (not a direct object), it cannot become the subject of a passive sentence. Keep sentences active.

✗ The exam was cheated on by several students.
✓ Several students cheated on the exam.

Usage

This phrasal verb is neutral and works in both spoken and written contexts, including official school reports. It is most often seen in the gerund form after phrases like 'caught cheating on' or 'accused of cheating on'.

Frequently Asked Questions

Does 'cheat on' always refer to romantic infidelity?

No — 'cheat on' has a second common meaning: using dishonest methods in an exam or test (e.g. 'cheat on a test'). When the object is a person in a romantic role (partner, husband, wife, etc.), it means sexual or romantic infidelity. Context almost always makes it clear which sense is intended.

Can I use 'cheat on' in formal writing?

It's better to avoid it in formal or academic writing, where 'be unfaithful to' or 'infidelity' are more appropriate. 'Cheat on' is neutral to informal and fits naturally in spoken conversation, social media, journalism, and fiction, but it can feel too casual in a formal essay or report.

How do I mention who the other person was — the one they cheated with?

Use the pattern 'cheat on [partner] with [other person]'. For example: 'He cheated on his girlfriend with a colleague.' This lets you name both the person who was betrayed and the third party in one sentence.

Why do people so often use 'has been cheating on' instead of 'cheated on'?

The present perfect continuous ('has been cheating on') emphasises that the behaviour was ongoing over a period of time, not just a single event. This fits the typical discovery story, where someone finds out the betrayal had been happening for months or years. 'Cheated on' (past simple) is used for a completed action or single event.

Can 'cheat on' be used without naming the person who was betrayed?

Yes — when the context is already clear, speakers sometimes drop the object entirely and just say 'he was cheating' or 'she cheated'. However, this is simply leaving out the object, not a different grammatical structure. Whenever you need to specify who was betrayed, you must use 'cheat on' followed by that person.

Does 'cheat on' always mean academic dishonesty?

No — 'cheat on' has two distinct meanings, and context tells you which one is meant. When the object is an assessment (exam, test, quiz), it means academic dishonesty. When the object is a person, it refers to a completely different situation. This page only covers the academic sense.

Can I use 'cheat on' without naming the specific exam?

Technically you can say 'he cheated on it', but this sounds unusual because speakers almost always name the specific assessment. It's much more natural to say 'he cheated on the exam' or 'he cheated on his homework' than to use a pronoun.

What kinds of assessments can follow 'cheat on'?

You can use 'cheat on' with any assessment-related noun: an exam, test, quiz, midterm, final, homework, assignment, coursework, or a standardised test like the SAT. It covers all forms of academic dishonesty during an assessment, not just copying someone else's work.

Is 'cheating on' more common than 'cheat on' in full sentences?

Yes — the gerund form 'cheating on' is very frequent, especially after phrases like 'caught cheating on', 'accused of cheating on', and 'expelled for cheating on'. These patterns appear constantly in news reports, school policies, and everyday conversation about academic integrity.

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