be on to
To know about something secret, to think someone is doing something wrong, or to be talking to someone.
Meanings
To have discovered or be close to discovering something significant.
"The investigative journalist felt she was on to something big with this story."
To have realised or suspected what someone is doing, especially something wrong or secretive.
"We'd better stop — the manager is on to us."
To be in contact with someone, typically by phone.
"I'll be on to the supplier first thing Monday morning to sort out the delay."
Context is important: 'the police are on to us' (they suspect us) vs. 'I'm on to something big' (I've discovered something) vs. 'I'll be on to them tomorrow' (I'll contact them). All senses are common in British English.
Commonly used with
Forms
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