Probability: Likely, Unlikely, Bound To, Definitely, Probably
Grammar Rule in 30 Seconds
Use specific words like 'likely' or 'bound to' to express how certain you are about a future event.
- Use 'definitely' for 100% certainty: 'It will definitely rain.'
- Use 'likely' or 'probably' for high probability: 'It is likely to snow.'
- Use 'bound to' for inevitable outcomes: 'You are bound to succeed.'
These words and expressions let you say how certain you are about something happening. Each has its own grammar pattern.
Likely / Unlikely + To-Infinitive
✓ She is likely to get the job.
✓ It is unlikely to snow in July.
Bound To — Almost Certain
✓ He is bound to forget — he always does.
✓ The traffic is bound to be bad on Friday.
Definitely / Probably — Position Rules
BEFORE will (positive) / BEFORE won't (negative)
✓ She will definitely call. / She will probably call.
✓ She definitely won't call. / She probably won't call.
| Expression | Certainty |
|---|---|
| is bound to / will definitely | ~95% — almost certain |
| is likely to / will probably | ~70% — probable |
| might / may | ~50% — possible |
| is unlikely to / probably won't | ~30% — improbable |
| definitely won't | ~5% — almost impossible |
Probability Structure Table
| Word | Structure | Certainty Level | Example |
|---|---|---|---|
|
Definitely
|
Subject + definitely + verb
|
100%
|
I definitely know.
|
|
Probably
|
Subject + probably + verb
|
75%
|
I probably know.
|
|
Likely
|
It is likely that / Subject is likely to
|
70%
|
It is likely to rain.
|
|
Unlikely
|
It is unlikely that / Subject is unlikely to
|
20%
|
It is unlikely to rain.
|
|
Bound to
|
Subject + be + bound to + verb
|
95%
|
It is bound to rain.
|
Common Contractions
| Full | Short |
|---|---|
|
It is likely
|
It's likely
|
|
He is bound to
|
He's bound to
|
|
It is definitely
|
It's definitely
|
Meanings
These expressions allow speakers to qualify statements, indicating the degree of certainty or expectation regarding an event.
High Certainty
Expressing that something is almost certain to happen.
“He is definitely coming.”
“They are bound to win.”
Moderate Probability
Expressing that something is more likely than not.
“It will probably rain.”
“She is likely to finish early.”
Unlikely/Negative
Expressing that something is not expected to happen.
“It is unlikely to snow today.”
“He is not likely to arrive on time.”
Reference Table
| Form | Structure | Example |
|---|---|---|
|
Affirmative
|
Subject + will + definitely + verb
|
I will definitely go.
|
|
Negative
|
Subject + will + probably + not + verb
|
I will probably not go.
|
|
Question
|
Is it likely that...?
|
Is it likely that he comes?
|
|
Bound to
|
Subject + to be + bound to + verb
|
They are bound to win.
|
|
Short Answer
|
Yes, it is definitely.
|
Yes, it is definitely.
|
|
Unlikely
|
It is unlikely to + verb
|
It is unlikely to snow.
|
Formality Spectrum
The meeting is bound to proceed as scheduled. (Work)
The meeting will definitely happen. (Work)
The meeting is definitely on. (Work)
The meet's a go. (Work)
The Certainty Scale
High
- Definitely 100%
Inevitable
- Bound to 95%
Expected
- Probably 75%
Low
- Unlikely 20%
Examples by Level
I will definitely go.
It will probably rain.
I am definitely happy.
We will probably eat.
She is likely to win.
It is unlikely to be cold.
They are bound to arrive soon.
I will definitely call you.
It is highly likely that he knows.
You are bound to make mistakes.
It is definitely not the right time.
He is unlikely to change his mind.
The project is bound to succeed given the budget.
It is improbable that the results will change.
She will almost certainly be there.
It is not likely that we will finish today.
Given the evidence, it is bound to be a success.
The outcome is, in all likelihood, predetermined.
He is definitely not the person for the job.
It is highly unlikely that the market will crash.
The inevitability of the event is bound to cause friction.
Such a conclusion is definitely beyond reasonable doubt.
It is statistically unlikely that this occurred by chance.
One is bound to encounter such difficulties eventually.
Easily Confused
Learners swap them because they mean similar things.
Both imply certainty.
Both mean 100%.
Common Mistakes
I go definitely.
I will definitely go.
It is likely rain.
It is likely to rain.
I probably will.
I will probably.
It is bound rain.
It is bound to rain.
He is probably to come.
He will probably come.
It is definitely not to happen.
It definitely won't happen.
I am likely go.
I am likely to go.
It is bound that it rains.
It is bound to rain.
He is unlikely that he wins.
He is unlikely to win.
Probably he will go.
He will probably go.
It is definitely to be a success.
It is definitely going to be a success.
He is likely that he will win.
It is likely that he will win.
The result is bound to be change.
The result is bound to change.
It is unlikely to be happen.
It is unlikely to happen.
Sentence Patterns
I will ___ go.
It is ___ to rain.
He is ___ to succeed.
It is ___ that we will finish.
Real World Usage
I'll probably be 5 mins late.
I am definitely interested in this role.
It is likely to rain.
The flight is bound to be delayed.
It will definitely arrive by 7.
This is definitely the best movie ever!
The 'Probably' Rule
Likely vs. Probably
Bound to
Softening
Smart Tips
Use 'bound to' for things that feel like a natural consequence.
Use 'unlikely' to sound professional.
Use 'definitely' to show enthusiasm.
Use 'probably' to keep things open.
Pronunciation
Stress
Stress the probability word for emphasis.
Falling
It will PROBably rain.
Certainty/Statement
Memorize It
Mnemonic
D-P-L-U-B: Definitely, Probably, Likely, Unlikely, Bound to.
Visual Association
Imagine a thermometer. 'Definitely' is at the top (red), 'Probably' is in the middle (orange), and 'Unlikely' is at the bottom (blue).
Rhyme
If you are sure, say definitely. If you think so, say probably.
Story
I definitely wanted to go. I probably had enough time. It was likely to be fun, but I was bound to be late.
Word Web
Challenge
Write 5 sentences about your day tomorrow using each of the 5 words.
Cultural Notes
British speakers often use 'likely' more conservatively.
Americans use 'definitely' very frequently in casual speech.
Australians often use 'probably' with a rising intonation.
Most of these words come from Latin roots (probabilis, definitus).
Conversation Starters
Do you think it will rain today?
Are you going to pass the exam?
Is the project bound to succeed?
Is it likely that the economy will improve?
Journal Prompts
Common Mistakes
Test Yourself
It is ___ to rain.
Which is correct?
Find and fix the mistake:
He is bound that he wins.
Arrange the words in the correct order:
All words placed
Click words above to build the sentence
Es probable que llueva.
Answer starts with: It ...
A: Will you be there? B: ___.
Use 'bound to' with 'success'.
Match each item on the left with its pair on the right:
Score: /8
Practice Exercises
8 exercisesIt is ___ to rain.
Which is correct?
Find and fix the mistake:
He is bound that he wins.
definitely / will / I / go
Es probable que llueva.
A: Will you be there? B: ___.
Use 'bound to' with 'success'.
Match 'Definitely'.
Score: /8
FAQ (8)
Yes, 'Probably, I will go' is common in speech.
No, it is an adjective. Use 'is likely to'.
'Bound to' is for future prediction; 'must' is for necessity.
Use 'not' after the auxiliary verb: 'I will probably not go'.
Some are (likely), some are casual (definitely).
Yes, 'Are you definitely coming?'
Yes, but 'unlikely' is more formal.
To express your level of certainty clearly.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
Es probable que
Subjunctive vs. Infinitive.
Il est probable que
Mood usage.
Wahrscheinlich
Word order flexibility.
Kamoshirenai
Suffixes vs. independent words.
Min al-muhtamal
Prepositional vs. Adjectival.
Keneng
Lack of conjugation.
Learning Path
Prerequisites
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