When something is considered "off limits," it means that it is not allowed or forbidden. There are several synonyms for this phrase, such as prohibited, forbidden, taboo, restricted, and inaccessible. When something is prohibited, it is not allowed by law or rules. Forbidden means something is not allowed for moral or ethical reasons. Taboo refers to things that are forbidden by a particular culture or society. Restricted means something has limitations on access or use, and inaccessible means something is not reachable or available to anyone. All of these synonyms convey the sense that there are certain things or places that are not allowed, and they should be avoided or approached with caution.