1 B1 idiomatic informal
To have discovered or be close to discovering something significant.
"The investigative journalist felt she was on to something big with this story."
inseparable
be on to
B1 informal inseparable transitive
To have discovered something important, to suspect someone, or to be in contact with someone.
In plain English
To know about something secret, to think someone is doing something wrong, or to be talking to someone.
What does "be on to" mean?
3 meanings, ordered from most common to least. Color-coded by CEFR level.
2 B1 idiomatic informal
To have realised or suspected what someone is doing, especially something wrong or secretive.
"We'd better stop — the manager is on to us."
inseparable
3 B1 neutral
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."
inseparable
Usage tip
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.
Words that pair with "be on to"
Natural word combinations native speakers use most often.
police something idea lead secret them
How to conjugate "be on to"
The five tense forms you'll use most often.
Base
be on to
I/you/we/they
3rd person
is on to
he/she/it
Past simple
was/were on to
yesterday
Past participle
been on to
have + pp
-ing form
being on to
continuous
Hear "be on to" in the wild
Listen to native speakers using "be on to" in real YouTube videos — click a clip to watch it on Looplines.
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