I doubt

Definitions

To express uncertainty or lack of conviction regarding the truth or existence of something.

To feel skeptical or suspicious about a person's motives or the likelihood of an event occurring.

Examples

I doubt that he will be able to finish the project by tomorrow.

I doubt whether it is going to rain this afternoon.

I doubt his sincerity after everything he has done.

Synonyms

I am skeptical I question I suspect I am unsure I hesitate I am unconvinced I wonder

Antonyms

I am certain I am sure I believe I trust I am convinced I accept I am confident