* Passage: This emphasizes the ability to move through something without obstruction.
* Openness: This refers to a lack of restrictions or limitations.
* Access: This refers to the ability to approach or enter something.
* Connection: This implies a lack of separation and the existence of a link between two things.
* Freedom: This emphasizes the absence of constraints and the ability to move freely.
The best opposite word will depend on the specific situation in which you are using the word "barrier."