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Adjectives: Forming opposites with prefixes

Adjectives: Forming opposites with Prefixes

To make the opposite of an adjective in English, we add a prefix (a small part) to the beginning of the word. There are five main prefixes: un-, in-, im-, ir-, and il-. Each prefix works with different adjectives, and there are spelling rules to help you know which one to use.

UN– is the most common prefix. We use it with most adjectives, especially simple ones. Examples: happy → unhappy (I feel unhappy today), kind → unkind (That was an unkind thing to say), lucky → unlucky (He’s very unlucky with the weather), comfortable → uncomfortable (This chair is uncomfortable), friendly → unfriendly (The dog seemed unfriendly). We use ‘un-‘ when the other prefixes don’t fit.

IN– is used with some adjectives, especially those from Latin. Examples: correct → incorrect (Your answer is incorrect), visible → invisible (The writing is invisible), expensive → inexpensive (I need an inexpensive hotel), complete → incomplete (Your homework is incomplete), capable → incapable (He feels incapable of helping). We write ‘in-‘ when the adjective doesn’t start with m, p, l, or r.

IM– is used when the adjective starts with the letters ‘m‘ or ‘p‘. This makes pronunciation easier – try saying ‘inpossible’ and you’ll see why we say ‘impossible’ instead! Examples: possible → impossible (It’s impossible to fly without a plane), polite → impolite (Don’t be impolite to your teacher), patient → impatient (I’m very impatient when I’m hungry), mature → immature (That joke was immature), perfect → imperfect (Everyone is imperfect).

IR– is used when the adjective starts with the letter ‘r‘. Again, this helps with pronunciation – ‘inresponsible’ is hard to say, but ‘irresponsible’ flows naturally. Examples: responsible → irresponsible (It’s irresponsible to drive fast), regular → irregular (English verbs are often irregular), relevant → irrelevant (That comment is irrelevant to our discussion), rational → irrational (I have an irrational fear of spiders), reversible → irreversible (The damage is irreversible).

IL– is used when the adjective starts with the letter ‘l‘. This follows the same pronunciation rule. Examples: legal → illegal (Stealing is illegal), logical → illogical (Your argument is illogical), legible → illegible (Your handwriting is illegible), literate → illiterate (Many people were illiterate 200 years ago), legitimate → illegitimate (That’s an illegitimate excuse).

Remember: the prefix matches the first letter to make speaking easier – im- before m/p, ir- before r, il- before l, and in- for other cases. When none of these rules apply, use un-!

Describing the World: Essential Adjectives and Their Opposites

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A2Lexis

1 Feelings and States: Happy ↔ Unhappy

Let’s start with adjectives that describe how we feel.

When something good happens, we feel happy. When something bad happens, we feel unhappy. Look at how we make the opposite:

happy → unhappy

The prefix un- makes the opposite meaning. It’s very common in English.

More examples with un-:

• comfortable ↔ uncomfortable
The chair is comfortable. = The chair feels good.
The chair is uncomfortable. = The chair feels bad.

• kind ↔ unkind
She is kind to animals. = She is nice to animals.
He was unkind to me. = He was not nice to me.

• lucky ↔ unlucky
I’m lucky today! = Good things happened to me.
He’s unlucky. = Bad things happened to him.

• safe ↔ unsafe
This street is safe at night. = No danger here.
That bridge is unsafe. = There is danger there.

• healthy ↔ unhealthy
Fruit is healthy food. = Good for your body.
Cake is unhealthy food. = Not good for your body.

✓ Pattern to remember: Most feeling adjectives use un- for the opposite.

Key Terms

happy feeling good and pleased

unhappy feeling sad or not pleased

comfortable feeling good and relaxed

uncomfortable not feeling good or relaxed

kind nice and helpful to other people

unkind not nice or helpful to other people

lucky having good things happen to you

unlucky having bad things happen to you

safe not in danger

unsafe in danger or not protected

healthy good for your body

unhealthy bad for your body

💬 Dialogue 1: Describing a New Apartment

Two friends, Emma and Tom, meet at a coffee shop. Tom moved to a new apartment last week and Emma wants to hear all about it.

Emma: “How’s your new apartment? Are you happy there?”

Tom: “It’s great! Very comfortable and the neighborhood is safe. I’m really happy!”

Emma: “That’s good to hear! My last apartment was so uncomfortable – the bed was terrible. Is it expensive?”

Tom: “No, it’s quite inexpensive actually. Only 600 euros a month. I’m very lucky!”

Emma: “Wow, that’s cheap for this city! I’m unlucky – I pay 900 euros and my area feels unsafe at night.”

Tom: “Oh no, that’s not good. Are you unhappy there? Maybe you can find a new place.”

Emma: “Yes, I’m quite unhappy. The expensive rent and unsafe streets are big problems for me.”

Tom: “I understand. I was unhappy in my old place too. But now I’m in a safe, comfortable, and inexpensive apartment!”

2 Possibility and Ability: Possible ↔ Impossible

Some adjectives talk about what we can do or what can happen.

Look at these words. They use different prefixes:

• possible ↔ impossible
It’s possible to learn English fast. = You can do it.
It’s impossible to fly without a plane. = You cannot do it.

• patient ↔ impatient
She is patient with children. = She waits and doesn’t get angry.
He is impatient in traffic. = He doesn’t like waiting.

• polite ↔ impolite
Say ‘please’ and ‘thank you’. That’s polite. = Good manners.
Don’t shout at people. That’s impolite. = Bad manners.

• complete ↔ incomplete
My homework is complete. = I finished it all.
This form is incomplete. = You didn’t finish it.

• dependent ↔ independent
A baby is dependent on its mother. = It needs help.
She is independent now. = She doesn’t need help.

✓ Pattern to remember: Words starting with p usually use im- for the opposite. Other words often use in-.

Key Terms

possible can happen or can be done

impossible cannot happen or cannot be done

patient able to wait without getting angry

impatient not able to wait, gets angry quickly

polite having good manners

impolite not having good manners

complete finished, with all parts done

incomplete not finished, missing parts

dependent needing help from others

independent not needing help from others

💬 Dialogue 2: Planning a Meeting Time

Two colleagues, Sarah and Mike, are trying to arrange a meeting to finish a project report. They’re talking in the office corridor on Monday morning.

Sarah: “Hi Mike! Is it possible to meet tomorrow morning? We need to finish the report.”

Mike: “Tomorrow morning is impossible for me. I have a meeting with the manager.”

Sarah: “OK, I understand. What about tomorrow afternoon? Is two o’clock possible?”

Mike: “Yes, that’s possible. Two o’clock is good for me. Should we work on the complete report or just part of it?”

Sarah: “The report is still incomplete. We need to finish the last two sections together.”

Mike: “I agree. The incomplete sections are difficult. Do you agree we need three hours?”

Sarah: “Hmm, I disagree. I think two hours is enough. We can work fast together.”

Mike: “OK, I agree with you. Two hours is possible. Let’s meet at two o’clock tomorrow and make the report complete!”

3 Honesty and Fairness: Honest ↔ Dishonest

These adjectives describe if something is right or wrong.

• honest ↔ dishonest
An honest person tells the truth. = They don’t lie.
A dishonest person lies. = They don’t tell the truth.

• fair ↔ unfair
The test was fair. = Everyone had the same chance.
The game was unfair. = Some people had a better chance.

Notice the prefix dis- in dishonest. This prefix is less common, but important.

Verbs with dis- prefix:

We also use dis- with some verbs:

• like ↔ dislike
I like coffee. = Coffee is good for me.
I dislike tea. = Tea is not good for me.

• agree ↔ disagree
I agree with you. = I think the same thing.
I disagree with Tom. = I don’t think the same thing.

• appear ↔ disappear
The sun appears in the morning. = You can see it.
The sun disappears at night. = You cannot see it.

✓ Pattern to remember: dis- often means ‘not’ or ‘the opposite of’.

Key Terms

honest always telling the truth

dishonest not telling the truth, lying

fair right and equal for everyone

unfair not right or equal

like think something is good or nice

dislike think something is not good or nice

agree think the same thing as another person

disagree not think the same thing as another person

appear become visible, you can see it

disappear become not visible, you cannot see it

4 Style and Cost: Formal ↔ Informal

These adjectives describe how something looks or how much it costs.

• formal ↔ informal
A suit is formal clothing. = For serious situations.
Jeans are informal clothing. = For relaxed situations.

• expensive ↔ inexpensive
The car is expensive. = It costs a lot of money.
The phone is inexpensive. = It doesn’t cost a lot of money.

Important note about ‘cheap’:

Many learners say ‘cheap’ for the opposite of expensive. But be careful!

cheap = costs little money (but sometimes means bad quality)
inexpensive = costs little money (neutral, not negative)

Compare:
‘This watch is cheap.’ = Maybe it’s bad quality.
‘This watch is inexpensive.’ = It costs little, but it’s good.

✓ Tip: Use inexpensive when you want to be polite.

Key Terms

formal serious and official in style

informal relaxed and casual in style

expensive costing a lot of money

inexpensive not costing a lot of money

5 Practice: Using Opposites in Real Situations

Now let’s see these adjectives in real conversations.

At a restaurant:

Emma: ‘This chair is very uncomfortable. Can we move?’
Tom: ‘Sure. That table looks better.’
Emma: ‘Perfect! This chair is much more comfortable.’

At the office:

Sarah: ‘Is it possible to finish this today?’
Mike: ‘No, it’s impossible. We need more time.’
Sarah: ‘OK, let’s finish it tomorrow.’

Shopping:

Customer: ‘This jacket is too expensive for me.’
Shop assistant: ‘We have some inexpensive jackets over there.’
Customer: ‘Great! I’ll look at those.’

Talking about people:

Tom: ‘My new boss is very patient. She explains everything slowly.’
Emma: ‘You’re lucky! My old boss was very impatient.’

At home:

Mike: ‘I disagree with this news story.’
Sarah: ‘Really? I agree with it completely.’

✓ Notice: We often use these opposites together in conversations to make comparisons.

6 Quick Reference: All Opposites Together

Here are all the opposite pairs from this lesson:

With un- prefix:
• happy ↔ unhappy
• comfortable ↔ uncomfortable
• kind ↔ unkind
• lucky ↔ unlucky
• safe ↔ unsafe
• healthy ↔ unhealthy
• fair ↔ unfair

With im- prefix:
• possible ↔ impossible
• patient ↔ impatient
• polite ↔ impolite

With in- prefix:
• complete ↔ incomplete
• dependent ↔ independent
• expensive ↔ inexpensive
• formal ↔ informal

With dis- prefix:
• honest ↔ dishonest

And with some verbs too:
• like ↔ dislike
• agree ↔ disagree
• appear ↔ disappear

✓ Remember: The prefix changes, but the pattern is always the same: prefix + word = opposite meaning.

✓ Common mistake: Don’t say ‘not happy’ when you can say ‘unhappy‘. Use the prefix form – it sounds more natural.

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