Cool MateCertainly vs Definitely vs Surely vs Undoubtedly vs Without a doubt
When to use each in English, with meaning, register, and examples.
Certainly
Definitely
Surely
Undoubtedly
Without a doubt
| Certainly | Definitely | Surely | Undoubtedly | Without a doubt | |
|---|---|---|---|---|---|
| Pronunciation | 🇬🇧 /["/ˈsɜːtnli/"]/🇺🇸 /["/ˈsɜːrtnli/"]/ | 🇬🇧 /["/ˈdefɪnətli/"]/🇺🇸 /["/ˈdefɪnətli/"]/ | 🇬🇧 /["/ˈʃʊəli//ˈʃɔːli/"]/🇺🇸 /["/ˈʃʊrli/"]/ | 🇬🇧 //ʌnˈdaʊtɪdli//🇺🇸 //ʌnˈdaʊtədli// | 🇬🇧 //wɪˈðaʊt ə daʊt//🇺🇸 //wɪˈðaʊt ə daʊt// |
| Meaning | Definitely; for sure. | For sure, without a doubt | certainly; without a doubt | Definitely; without a doubt. | Definitely true; no question about it. |
| Example | Without treatment, she will **almost certainly** die. | I definitely remember sending the letter. | Surely we should do something about it? | She is undoubtedly the best candidate for the position. | She is, without a doubt, the most talented singer in the group. |
| Register | Neutral | Neutral | Neutral | Formal | Neutral |
| How common | Top 1,000 (very common) | Top 1,000 (very common) | Top 2,000 (common) | Top 5,000 (fairly common) | Top 2,000 (common) |
| CEFR level | A2 | A2 | B1 | C1 | - |
| Part of speech | adverb | adverb | adverb | adverb | |
| Collocations | certainly agree, certainly possible, certainly not, certainly true, certainly yes | definitely agree, definitely believe, definitely know | surely believe, surely know, surely must | undoubtedly true, undoubtedly clear, undoubtedly helpful | believe without a doubt, know without a doubt, say without a doubt |
| Antonyms | uncertainly, doubtfully | doubtfully, uncertainly | doubtfully, unsure | doubtfully, questionably, uncertainly | - |
| Common mistakes | 'Certainly' is often incorrectly used in place of 'certain' in adjectives., Learners might confuse 'certainly' with 'definitely' without noticing the subtle nuance., Some learners use 'certainly' in inappropriate contexts, such as casual greetings. | Often confused with 'defiantly' which means resisting authority., Sometimes spelled incorrectly as 'definately'. | Confusing 'surely' with 'sure' — 'sure' can be an adjective., Using 'surely' as a response when a simple 'yes' would suffice., Omitting 'surely' in a sentence where it clarifies certainty. | Confused with 'undoubtably', which is incorrect., Omitting it when certainty is implied., Using it in informal contexts where 'definitely' is more suitable. | Used with incorrect verb forms (e.g., 'Without a doubt, he is the best.' should be 'Without a doubt, he is the best choice.'), Often confused with similar phrases like 'without question,' which can have a slightly different tone. |
| Usage notes | Use 'certainly' when you want to emphasize affirmation or agreement. It is more formal than 'sure' and works well in professional settings, but might feel too strong in casual conversations. | Use 'definitely' to emphasize certainty. It fits well in both spoken and written English. Avoid using it in overly formal contexts where alternatives like 'certainly' might be more suitable. | Use 'surely' to express certainty. It’s appropriate in both spoken and written contexts but is more common in formal discussions. Avoid using it in very casual conversations where simpler words like 'definitely' might fit better. | Used to emphasize certainty or strong belief; typically in formal writing or speeches, not common in casual conversation. | Used to express strong certainty. Suitable for both spoken and written forms. Avoid in overly formal contexts. |
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Frequently asked questions: Certainly vs Definitely vs Surely vs Undoubtedly vs Without a doubt
What's the difference between Certainly, Definitely, Surely, Undoubtedly, and Without a doubt?
Certainly: Definitely; for sure. Definitely: For sure, without a doubt Surely: certainly; without a doubt Undoubtedly: Definitely; without a doubt. Without a doubt: Definitely true; no question about it.
Which is more formal: Certainly, Definitely, Surely, Undoubtedly, and Without a doubt?
Undoubtedly is the most formal of these.
Which is more advanced: Certainly, Definitely, Surely, Undoubtedly, and Without a doubt?
Undoubtedly is the highest level, at C1, on the CEFR scale.
Can you show an example of each?
Certainly: Without treatment, she will **almost certainly** die. Definitely: I definitely remember sending the letter. Surely: Surely we should do something about it? Undoubtedly: She is undoubtedly the best candidate for the position. Without a doubt: She is, without a doubt, the most talented singer in the group.
Can I use Certainly, Definitely, Surely, Undoubtedly, and Without a doubt interchangeably?
Not always. Certainly, Definitely, Surely, Undoubtedly, and Without a doubt 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.