These six adjectives answer different questions. Some describe whether something can happen; others describe practical plans, believable explanations or expected results. They do not form one simple scale from uncertain to certain.
- Possible means something can happen or be done. It does not tell you that the chance is high. It is possible that we will see snow tonight.
- Feasible means something can realistically be done with the time, money, skills or equipment available. Finishing the repairs today is feasible if both mechanics help.
- Viable means something can work successfully, especially over time. It often describes businesses, plans and solutions. The café needs more regular customers to remain viable.
- Plausible means an explanation, claim or idea sounds reasonable and could be true. It does not mean it has been proved. A flat battery is a plausible explanation for the problem.
- Probable means something is likely to happen or be true, but is not certain. A delay is probable because of the storm.
- Inevitable means something is certain to happen and cannot be avoided. Without urgent repairs, further damage is inevitable.
A project may be feasible to launch but not viable as a lasting business. Similarly, a story can sound plausible without being the most probable explanation. Choose the adjective that matches your question: practical limits, lasting success, believability or likelihood.