Cool MateDefinitely vs They certainly do
When to use each in English, with meaning, register, and examples.
Definitely
Top 1,000 (very common)A2adverb
They certainly do
Top 5,000 (fairly common)
Most common: Definitely
| Definitely | They certainly do | |
|---|---|---|
| Pronunciation | 🇬🇧 /["/ˈdefɪnətli/"]/🇺🇸 /["/ˈdefɪnətli/"]/ | 🇬🇧 //ðeɪ ˈsɜːtənli duː//🇺🇸 //ðeɪ ˈsɜrtənli du// |
| Meaning | For sure, without a doubt | They really do something. |
| Example | I definitely remember sending the letter. | If you think they are friendly, they certainly do seem that way. |
| Register | Neutral | Neutral |
| How common | Top 1,000 (very common) | Top 5,000 (fairly common) |
| CEFR level | A2 | - |
| Part of speech | adverb | |
| Collocations | definitely agree, definitely believe, definitely know | do say, do believe, do enjoy |
| Antonyms | doubtfully, uncertainly | - |
| Common mistakes | Often confused with 'defiantly' which means resisting authority., Sometimes spelled incorrectly as 'definately'. | Confused with 'they certainly don't' which has an opposite meaning., Using it in overly formal contexts where a simple 'yes' is more appropriate. |
| Usage notes | 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 this phrase to affirm or emphasize something that has been said. It's more emphatic than just saying 'yes'. Suitable for conversations but not very formal writing. |
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Frequently asked questions: Definitely vs They certainly do
What's the difference between Definitely and They certainly do?
Definitely: For sure, without a doubt They certainly do: They really do something.
Which is more common: Definitely and They certainly do?
Definitely is the most common in everyday English.
Can you show an example of each?
Definitely: I definitely remember sending the letter. They certainly do: If you think they are friendly, they certainly do seem that way.
Can I use Definitely and They certainly do interchangeably?
Not always. Definitely and They certainly do 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.