怀疑
huáiyí
to doubt, to suspect
verb
Example
我怀疑他说的话不是真的。
Wǒ huáiyí tā shuō de huà bú shì zhēn de.
I suspect that what he said is not true.
This word can express both doubt about facts and suspicion about people's motives. It's commonly used in daily conversation and formal writing.