ENGLISH
REFERENCE

be in on

phr. v..
C1 Advanced Oxford

phr. v.. to be part of a group that knows a secret or is involved in a private plan.

phr. v.. to be privy to or a participant in a secret, scheme, or specific activity.


SIMPLE

Are you in on the surprise party?

CONTEXTUAL

Only a few managers were in on the plan to sell the company before the news went public.

COMPLEX

While the public remained unaware of the impending merger, several high-level executives had been in on the negotiations for months.

Particles
in on
Separability
inseparable
Pattern
be + in + on + object
Usage

usually followed by a noun phrase representing a secret, joke, or plan.

Teaching tip

contrast with 'be in' (to be at home/office); the addition of 'on' shifts the meaning from physical location to shared knowledge or participation.

Pitfall

He was in the secret.He was in on the secret.the preposition 'on' is required to show participation in a plan or secret.

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