What is the opposite of openly?

The opposite of "openly" depends on the context, but here are some possibilities:

In terms of secrecy/visibility:

* Secretly

* Covertly

* Privately

* Subtly

* Behind closed doors

* In secret

In terms of honesty/transparency:

* Dishonestly

* Deceptively

* Hidden

* Concealed

* Masked

In terms of willingness to engage:

* Closed off

* Unwilling

* Reluctant

* Hesitant

In terms of accessibility:

* Closed

* Restricted

* Limited

* Exclusive

The best opposite will depend on the specific situation and what you're trying to convey.