What is a antonym for certain?

Here are some antonyms for "certain," depending on the specific context:

General antonyms:

* Uncertain

* Doubtful

* Indefinite

* Ambiguous

* Unclear

* Vague

More specific antonyms:

* Possible (if referring to likelihood)

* Unlikely (if referring to likelihood)

* Doubtful (if referring to belief)

* Contingent (if referring to dependence on conditions)

* Unpredictable (if referring to predictability)

The best antonym will depend on the specific meaning you want to convey.