be onto
phrasal verbbe onto somebody
- (informal) to know about what somebody has done wrong
- She knew the police would be onto them.
- to be talking to somebody, usually in order to ask or tell them something
- They've been onto me for ages to get a job.
be onto something
- to know about something or be in a situation that could lead to a good result for you
- Scientists believe they are onto something big.
- She's onto a good thing with that new job.