General:
* Accessible: This implies that something is easy to reach or use.
* Available: This means that something is ready for use or can be obtained.
* Free: This indicates that something is not restricted or limited.
* Unclosed: This is a literal opposite of closed.
* Unsealed: This implies that something is not protected or hidden.
Specific:
* Uncovered: This refers to something that is not hidden or covered.
* Exposed: This implies that something is vulnerable or unprotected.
* Unfastened: This refers to something that is not tied, closed, or secured.
* Revealed: This implies that something has been made visible or known.
* Published: This refers to something that has been made public.
Figurative:
* Candid: This refers to someone who is honest and open in their communication.
* Frank: This implies that someone is direct and straightforward.
* Forthcoming: This indicates that someone is willing to share information or cooperate.
* Transparent: This refers to someone who is honest and open about their intentions.
To choose the best synonym, consider the specific meaning of "open" in the context of your sentence.