6.4 Informal English and Idioms
Master idioms, slang, phrasal verbs and colloquialisms, and learn when to use informal language.
Informal English and Idioms
If someone tells you it is "raining cats and dogs," you do not look out the window expecting to see animals falling from the sky. You understand it means heavy rain. This is the magic of idiomatic language — expressions whose meaning cannot be understood from the individual words alone.
English is extraordinarily rich in idioms, phrasal verbs, slang, and colloquial expressions. Native speakers use them constantly in everyday speech, and they appear frequently in films, songs, novels, and social media. Understanding — and using — idiomatic language makes your English more natural, expressive, and engaging.
However, informal language comes with rules of its own. Knowing when to use it is just as important as knowing what it means. Using slang in a formal essay will lose you marks; using overly formal language with friends will sound strange.
In this chapter, you will learn:
- What idioms are and how to interpret them
- Common phrasal verbs and how they differ from single-word verbs
- The difference between slang and colloquial language
- How to identify register — the level of formality in language
- When informal language is appropriate and when to avoid it
An idiom is a fixed expression whose meaning cannot be understood from the literal meaning of its individual words. Idioms are deeply embedded in culture, and every language has them.
Common English idioms and their meanings:
| Idiom | Meaning |
|---|---|
| Break the ice | Start a conversation in an awkward situation |
| Hit the nail on the head | Describe something exactly right |
| A piece of cake | Something very easy |
| Spill the beans | Reveal a secret |
| Bite the bullet | Face a difficult situation with courage |
| Under the weather | Feeling ill |
| Cost an arm and a leg | Very expensive |
| Once in a blue moon | Very rarely |
| The ball is in your court | It is your turn to act or decide |
| Burn the midnight oil | Work or study late into the night |
| Kill two birds with one stone | Accomplish two things with one action |
| Let the cat out of the bag | Accidentally reveal a secret |
Where do idioms come from?
Many idioms have historical origins:
- "Break a leg" (good luck) may come from theatre superstition
- "Bury the hatchet" (make peace) comes from a Native American peace ceremony
- "Saved by the bell" may come from boxing, where the round-ending bell saves a struggling fighter
Why are idioms important?
- They make language more vivid and engaging
- They appear frequently in authentic English texts (novels, films, news)
- Using them shows a high level of language competence
- They are often tested in English exams
A phrasal verb is a verb combined with one or two particles (prepositions or adverbs) that create a new meaning different from the original verb.
Examples showing how the particle changes meaning:
The verb "look" + different particles:
- look up = search for information ("Look up the word in the dictionary")
- look after = take care of ("Can you look after my dog?")
- look forward to = anticipate with pleasure ("I look forward to meeting you")
- look down on = feel superior to ("She looks down on people who didn't go to university")
- look into = investigate ("The police are looking into the matter")
The verb "give" + different particles:
- give up = stop trying ("Don't give up — keep practising!")
- give in = surrender / yield ("After hours of arguing, she finally gave in")
- give away = donate / reveal ("He gave away all his old clothes")
- give out = distribute ("The teacher gave out the worksheets")
Why are phrasal verbs important?
- They are extremely common in everyday English
- Academic writing prefers single-word alternatives: put off → postpone, give up → abandon, find out → discover
- Understanding them is essential for reading fiction, watching films, and conversing naturally
Separable vs. inseparable phrasal verbs:
- Separable: "Turn off the light" = "Turn the light off" (the object can go in the middle)
- Inseparable: "Look after the children" (NOT "Look the children after")
The register spectrum:
Frozen / Static — The most formal; fixed language that never changes.
- Legal documents: "Hereby the party of the first part..."
- Religious texts: "Our Father, who art in heaven..."
- National anthems and oaths
Formal — Professional, academic, official communication.
- "I am writing to express my concern regarding..."
- "The research findings indicate that..."
- No contractions, no slang, complex sentence structures
Consultative — Standard professional interaction.
- "Could you explain what happened?"
- "I would suggest that we consider..."
- Polite, clear, but not stiff
Casual / Informal — Everyday conversation with people you know.
- "Hey, what's up?"
- "That movie was sick!" (= really good)
- Contractions, slang, incomplete sentences, humour
Intimate — Private language between very close people.
- Pet names, inside jokes, family shorthand
- "You know the thing" (context is understood without explanation)
Why register matters in English class:
- Exam essays require formal or consultative register
- Creative writing can use casual register in dialogue
- Letters to the editor use formal register
- A blog post might use casual register
- Mismatching register and context is a common exam mistake
Rewrite the following informal message as a formal email, and explain the specific changes in language.
Informal text message: "Hey Mr. T! Just a heads up — gonna be late for class tmrw. My bus is always messing up lol. Can u cut me some slack? Cheers!"
Subject: Advance Notice of Late Arrival — Tuesday
Dear Mr. Thompson,
I am writing to inform you that I may arrive late to class tomorrow morning. Unfortunately, my bus service has been unreliable recently, and I anticipate a delay of approximately 10–15 minutes.
I apologise for any inconvenience this may cause and will ensure I catch up on any material I miss. I would appreciate your understanding.
Kind regards,
Emma Hansen
Changes explained:
| Informal | Formal | Why |
|---|---|---|
| Hey Mr. T | Dear Mr. Thompson | Full name, formal greeting |
| heads up | advance notice | Idiom replaced with formal equivalent |
| gonna | I may / I anticipate | Contraction expanded; hedging language |
| tmrw | tomorrow | No abbreviations |
| messing up | has been unreliable | Phrasal verb replaced with formal adjective |
| lol | (removed) | No internet slang |
| cut me some slack | I would appreciate your understanding | Idiom replaced with polite formal phrase |
| Cheers | Kind regards | Formal closing |
| u | you | Full spelling |
The content is the same — but the register is completely different. Choosing the right register shows respect for the context and audience.
Read this dialogue between two teenagers and identify the slang and colloquial expressions. What do they mean?
"Dude, that test was no joke. I was totally blanking on the last question."
"Same. I thought I'd nailed it but then I second-guessed myself."
"At least it's over. Wanna grab some food? I'm starving."
"For sure. Let's bounce."
1. "Dude" — informal address for a friend (originally American surfer slang, now universal)
2. "no joke" — serious; difficult (colloquial intensifier)
3. "totally blanking" — completely unable to remember or think of something
4. "nailed it" — did it perfectly; succeeded
5. "second-guessed myself" — doubted my own answer after initially choosing it
6. "Wanna" — contraction of "want to" (informal spoken form)
7. "grab some food" — get something to eat (informal phrasal verb)
8. "I'm starving" — I'm very hungry (hyperbole — not literally starving)
9. "For sure" — definitely; yes (casual affirmation)
10. "Let's bounce" — let's leave (slang)
Key insight: This dialogue is perfectly appropriate for a casual conversation between friends. However, if you wrote these expressions in a formal essay, they would be inappropriate. The skill is not avoiding informal language entirely — it is knowing when and where to use it.
In creative writing: Using slang in dialogue makes characters sound realistic and authentic. The dialogue above would work perfectly in a short story about teenagers.
What does the idiom "break the ice" mean?
What is a phrasal verb?
Which register would be most appropriate for a school essay about climate change?
"She decided to look into the matter after her colleague spilled the beans." This sentence contains two idiomatic expressions. Which pair correctly identifies them?
Which of these is the correct formal equivalent of the phrasal verb "put off"?
A student writes in an exam essay: "The government needs to get their act together and sort out the healthcare mess." What is the problem with this sentence in an academic context?
Consider the expression "It's not rocket science." This idiom means "It's not difficult." Why might this idiom be problematic to use when communicating with non-native English speakers from different cultural backgrounds?
In a short story, a character uses highly formal language when talking to friends at a party: "I find this social gathering most enjoyable. Would you be so kind as to pass me that beverage?" What effect does this register mismatch create, and how might an author use it intentionally?
Oppsummering
In this chapter you have learned:
- Idioms: Fixed expressions whose meaning cannot be worked out from the individual words.
- Phrasal verbs: Verbs combined with a particle that change the verb's meaning (e.g. give up, look after).
- Slang and colloquialisms: Informal language used in casual, everyday contexts.
- Register: Matching your language to the situation, and knowing when informal English is appropriate.
Key terms
| Term | Explanation |
|---|---|
| Idiom | Fixed phrase with a non-literal meaning |
| Phrasal verb | Verb + particle that changes meaning |
| Slang | Very informal, often group-specific vocabulary |
| Register | The level of formality of language |
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