Cool MateCannot vs Impossible vs Unable
When to use each in English, with meaning, register, and examples.
Cannot
Impossible
Unable
| Cannot | Impossible | Unable | |
|---|---|---|---|
| Pronunciation | 🇬🇧 /["/ˈkænɒt/"]/🇺🇸 /["/ˈkænɑːt/"]/ | 🇬🇧 /["/ɪmˈpɒsəbl/"]/🇺🇸 /["/ɪmˈpɑːsəbl/"]/ | 🇬🇧 /["/ʌnˈeɪbl/"]/🇺🇸 /["/ʌnˈeɪbl/"]/ |
| Meaning | to be unable to do something | Not able to happen or be done. | not able to do something |
| Example | I cannot believe the price of the tickets! | Climbing that mountain seems impossible without proper training. | I was unable to attend the meeting due to a family emergency. |
| Register | Neutral | Neutral | Neutral |
| How common | Top 1,000 (very common) | Top 1,000 (very common) | Top 2,000 (common) |
| CEFR level | A1 | A2 | B1 |
| Part of speech | adjective | ||
| Collocations | cannot believe, cannot wait, cannot afford | appear, be, look, absolutely, completely, downright, for, be, become, find somebody, really, absolutely, completely | appear, be, feel, completely, quite, totally, unwilling or unable |
| Antonyms | can, able | possible, feasible, achievable | able, capable |
| Common mistakes | Confused with 'can not' — it's always one word in negative form., Using 'cannot' in too formal a context — prefer 'can't' in casual speech., Incorrectly using 'cannot' in past tense situations. | 'Impossible' is sometimes confused with 'unbelievable' but they are not the same., Learners might use 'impossible' to describe very challenging tasks instead of things that cannot be done at all., 'Impossible' is often incorrectly combined with less strong modifiers, like 'very impossible'. | Confused with 'unable to' and 'not able to' — they mean the same but usage can vary., Using 'unable' without a following action verb., Misplacing adjectives — remember 'unable' always describes capability. |
| Usage notes | Use 'cannot' in any situation where something is impossible. Avoid using it in informal contexts where 'can't' is more common. | Use 'impossible' to describe something that cannot be achieved. It’s suitable for both spoken and written English but may be too strong in polite contexts. | Use 'unable' in situations where someone or something lacks the ability to perform an action. It's appropriate in both spoken and written contexts, but avoid in very casual conversations. |
See it in real clips
Frequently asked questions: Cannot vs Impossible vs Unable
What's the difference between Cannot, Impossible, and Unable?
Cannot: to be unable to do something Impossible: Not able to happen or be done. Unable: not able to do something
Which is more advanced: Cannot, Impossible, and Unable?
Unable is the highest level, at B1, on the CEFR scale.
Are Cannot, Impossible, and Unable the same CEFR level?
Cannot: A1, Impossible: A2, Unable: B1 on the CEFR scale.
Can you show an example of each?
Cannot: I cannot believe the price of the tickets! Impossible: Climbing that mountain seems impossible without proper training. Unable: I was unable to attend the meeting due to a family emergency.
Can I use Cannot, Impossible, and Unable interchangeably?
Not always. Cannot, Impossible, and Unable are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.