be onto (one)
1. To have knowledge, be suspicious, or be aware of one's actions, behavior, or intention. You'd better tread carefully—I'm onto you now. The police are onto us! Everybody run! The FBI is onto us now? Oh man, we're doomed!
2. To be in contact with one at a given point in time. I'll be onto you tomorrow about the details of our meeting. I was onto John yesterday about where he wants to go for his birthday. Look, I was onto Grandma earlier, and she really doesn't want to do anything big for her birthday.
Farlex Dictionary of Idioms. © 2024 Farlex, Inc, all rights reserved.