Any likely synonym you choose must survive two tests, sense and sentence pattern. Before a noun, probable and expected slot in neatly; after is likely to, the swaps are apt, liable and prone; and when likely works as an adverb, probably is almost always the cleaner word.
Each option carries its own mood. Prone and liable usually hint at something unwelcome, plausible is about whether a story can be believed, and promising is pure optimism. The tables and swaps below keep those moods straight.
Swatch at a glance
Best swaps
probable, expected, apt, probably, plausiblePart of speech
Adjective; also an adverb, especially in American EnglishMost formal
in all likelihood, presumablyMost casual
chances are, a safe betStrongest
bound to, all but certainAntonyms
unlikely, improbable, doubtfulWatch out
Liable and prone point to bad outcomes. Say prone to errors, not prone to success.
Grouping each likely synonym by job
| Use | Words | Sample line |
|---|---|---|
| Before a noun | probable, expected, anticipated | The probable cause was a loose wire. |
| Likely to do | apt, liable, prone, inclined, bound | Old ladders are apt to wobble. |
| Believable | plausible, credible, reasonable | Her excuse sounded plausible. |
| Promising | promising, suitable, up-and-coming | He looks like a promising candidate. |
| Adverb | probably, presumably, in all likelihood | They will probably arrive late. |
Swaps rarely cross rows. You cannot say she is probable to win; you must say she is likely to win or she will probably win.
How sure are you: the odds strip
Certainty grows chip by chip. Plausible says a claim is believable, the softest hint that it may come true. Probable is the true match for likely, meaning better than even odds. Expected adds that people are planning around it. All but certain leaves almost no room for doubt, and bound to removes it entirely.
Conceivable and possible sit below this strip. They are weaker than likely, so treat them as softer neighbors, not swaps. If a forecast says rain is likely and you write possible, you have changed the forecast.
Apt, liable and prone compared
These three all follow the pattern be X to do, and they are easy to confuse.
| Word | Tone | Example |
|---|---|---|
| apt | neutral, a natural tendency | Toddlers are apt to put things in their mouths. |
| liable | a risk, often negative | The path is liable to flood in spring. |
| prone | a habit or weakness | This printer is prone to jamming. |
Notice that prone often takes to plus a noun or an ing word, while apt and liable take the base verb. For words about chance and truth, see possible synonyms and certain synonyms.
Sentences with likely swapped out
- The likely winner is the blue team becomes the probable winner is the blue team.
- Prices are likely to rise becomes prices are expected to rise.
- He will likely be late becomes he will probably be late.
- That is a likely story, said with a frown, becomes that story is hard to believe.
- She is likely to forget her keys becomes she is apt to forget her keys.
- We spotted a likely place to camp becomes we spotted a suitable place to camp.
A text to a friend: "Likely running ten minutes late, likely stuck behind a tractor." Trim it to one hedge: "Running ten minutes late, probably stuck behind a tractor." Probably reads like a person talking instead of a weather report.
Hedging in essays with likely and its cousins
Good academic writers hedge on purpose. Probable, presumably and in all likelihood signal judgment without overclaiming. Plausible suits arguments and explanations, not events. Avoid bound to unless you have strong evidence, because it promises the outcome.
The adverb use, as in it will likely rain, is standard in American English but sounds informal to many British readers, who prefer probably. When unsure, probably is safe everywhere. Extra hedges, such as arguably and tends to, are collected with the academic writing vocabulary.
Opposites, from doubtful to far-fetched
Unlikely and improbable are the plain antonyms. Doubtful adds personal skepticism, remote fits chances (a remote possibility), and far-fetched or implausible reject an explanation as hard to believe.
- A delay is improbable but not impossible.
- His theory about the missing socks sounds far-fetched.
For the strongest opposite, see impossible synonyms.
Frequently asked questions
Which word replaces likely most often?
Probable before a noun and probably as an adverb. Expected works well for forecasts and plans.
Is probable exactly the same as likely?
Very close in meaning, but the grammar differs. You can say it is likely to snow, yet not it is probable to snow; write snow is probable instead.
Can likely be used as an adverb?
Yes, especially in American English: they will likely agree. Many British writers prefer probably, or most likely.
What word suggests a bad outcome is likely?
Liable and prone. A roof liable to leak or a car prone to stalling both warn of trouble.
Which antonym of likely sounds most formal?
Improbable is the formal choice. Unlikely is neutral, and doubtful adds a personal note of skepticism.
What does that's a likely story mean?
It is sarcasm. The speaker means the story is not believable at all, so the real meaning is the opposite of the words.