Adverbs of Probability

Adverbs of Probability

Adverbs of probability help you show how sure you are about something — from complete certainty to serious doubt.

They are extremely common in everyday English and appear frequently in Cambridge B2 First and C1 Advanced exams, especially in speaking, essays, reports, and discussions.

Instead of simply stating facts, these adverbs allow you to soften, strengthen, or hedge your ideas — which makes your English sound more natural, accurate, and confident.

In this lesson, you will learn the most common adverbs of probability, their meanings, correct sentence position, and how to choose the right one depending on how certain you really are.

Definitely

Meaning: without any doubt; certainly.

• I’ll definitely call you once I arrive home.
• He definitely needs more practice before the concert.

Certainly

Meaning: surely; without any doubt.

• Sally certainly deserves the award for her hard work.
• Mandy certainly handled the situation with grace.

Surely

Meaning: without a doubt; certainly.

• Surely, he must have forgotten the appointment.
• The new policy will surely improve the company’s performance. 

Probably

Meaning: likely to happen or be true.

• They will probably arrive late due to the traffic.
• Peter will probably finish the project by tomorrow.

Likely

Meaning: having a high probability; probable.

• It is likely that she will get the job.
• Manchester United are likely to win the game given their strong performance.

Note: Likely is most commonly used as an adjective, often in the structure It is likely that… or be likely to…

Possibly

Meaning: maybe; indicating a weak possibility.

• They might possibly visit us next weekend.
• We could possibly see some rain later in the day.

Perhaps

Meaning: maybe; possibly.

• Perhaps there is another solution to this problem.
• She will perhaps change her mind after some time.

Maybe

Meaning: possibly; perhaps.

• Maybe we should try a different approach.
• Maybe the weather will improve later in the day.

Unlikely

Meaning: not probable; not expected to happen.

• It is unlikely that they will change their plans.
• She is unlikely to attend the meeting due to prior commitments.

Doubtfully

Meaning: with uncertainty or doubt.

• He looked at her doubtfully when she told the story.
• Peter shook his head doubtfully at the suggestion.

Note: Doubtfully is less common in everyday English. Learners often prefer structures with I doubt… or It’s unlikely that…

Key points to remember about adverbs of probability

Position in sentences

Adverbs of probability usually come before the main verb but after the verb “to be”.

She will probably come. / She is definitely coming. 

They can also be placed at the beginning or end of a sentence for emphasis.

Maybe they will join us. / They will join us, probably.

Degree of certainty

Adverbs like “definitely,” “certainly,” and “surely” express a high degree of certainty.

Adverbs like “probably” and “likely” indicate a strong possibility but not absolute certainty.

Adverbs like “possibly,” “perhaps,” and “maybe” suggest a weaker possibility.

Adverbs like “unlikely” and “doubtfully” indicate a low probability.

Exam tip:

Use adverbs of probability to clarify your level of certainty about an action or event.

Remember to be mindful of the context and choose the appropriate adverb based on how certain you are.

In Cambridge exams, using adverbs like probably, perhaps, and unlikely helps you avoid sounding too absolute — especially in essays and speaking tasks where you are asked to give opinions or discuss possibilities.

Adverbs of probability

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