be on to something

be on to (someone or something)

1. To have knowledge, be suspicious, or be aware of someone's actions, behavior, or intention. You'd better tread carefully, I'm on to you now. The police are on to us! Everybody run!
2. To be in contact with someone at a given point in time. I'll be on to you tomorrow about the details of our meeting. I was on to John yesterday about where he wants to go for his birthday.
3. To discover, realize, or be in the process of doing something of great importance, value, or insight. Great work on this essay, Lindsay. I really think you're on to something here. Scientists now believe they may be on to a cure for cancer.
See also: on
Farlex Dictionary of Idioms.

be on to something

have an idea or information that is likely to lead to an important discovery. informal
See also: on, something
Farlex Partner Idioms Dictionary
See also:
  • be on to
  • be on to (someone or something)
  • be on to someone
  • be onto
  • be onto somebody
  • be onto something
  • tread
  • tread lightly
  • step/tread on someone's toes, to
  • cover