1A transitive verb meaning to doubt, distrust, or suspect someone or something; to have reservations about the truth of a statement or action.
彼の話を最初から疑ってかかるのはよくない。
It's not good to start by doubting his story from the outset.
警官は彼を共犯者ではないかと疑った。
The officer suspected him of being an accomplice.
その噂を疑う理由はないように思える。
It seems there is no reason to doubt that rumor.