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Certainly vs. Definitely

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2:43 min read
  Angbeen Chaudhary  —  Grammar Tips
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English is quite a confusing language when it comes to certain words which have very similar meanings and makes it hard for the speakers and writers to determine when to use which word. Among the list of these words, certainly and definitely definitely fall and have been confusing people since forever. Consider the examples below:

He is definitely in town, I saw him this morning.

He is certainly in town, I saw him this morning.

Which of the above two sentences is correct? Can certainly and definitely be used interchangeably? If no, what is the difference between the two? All these questions will be answered in this article which will highlight the meaning, usage and examples of both the words.


The word certainly originated from Middle English: from Old French, based on Latin certus ‘settled, sure’. The word definitely originated in mid 16th century: from Latin definitus ‘defined, set within limits’, past participle of definire.

Certainly as adverb:

Certainly is used as an adverb in English language where it means to emphasize the speaker's belief that what is said is true.

The prestigious address certainly adds to the firm's appeal.

Certainly also means to indicate that a statement is made as a concession or contrasted with another.

Our current revenues are certainly lower than anticipated.

Another usage of certainly is to express complete agreement with something that has just been said.

‘A good idea,’ she agreed. ‘Certainly!’

Definitely as adverb:

Certainly vs. Definitely

Definitely is used as an adverb in English language where it means without doubt (used for emphasis).

I shall definitely be at the airport to meet you.

Definitely also means in a definite manner; clearly.

We couldn't plan to go elsewhere until we had heard from you more definitely.


The mother definitely has love for her child.

And the Nose definitely turned away. (Nikolai Gogol)

He verily thought he had young live frogs in his belly, qui vivebant ex alimento suo , that lived by his nourishment, and was so certainly persuaded of it, that for many years following he could not be rectified in his conceit.

So this was my future home, I thought! Certainly it made a brave picture. I had seen similar ones fired-in on many a Heidelberg stein.

The high oil prices are certainly not wholesome for the economy, how could you think otherwise?

Definitely or certainly:

So what is the difference between the two adverbs? They seem very similar to each other but you should know that they can’t always be used interchangeably. The only differences are in the writer's intent within the context of a sentence or paragraph.  Think of it in terms of answering a question. "Will you come to our party this weekend?" Definitely!  "Will the house be clean by the time I get back."  Certainly.   Also, they might be chosen for differently levels of certainty. I'm definitely coming to the party. Even if I have to move some other things around on my schedule, I will make time to come to your party.  And the house will be cleaned by the time I get home, although the persons doing the cleaning are guaranteeing it but not excited about the task.

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