What is the meaning of Significant other in a legal document?

In a legal document, "significant other" typically refers to a person with whom someone has a close, committed relationship, akin to that of a spouse or partner, but without formal legal recognition such as marriage. This term can encompass various types of relationships, including domestic partnerships or long-term relationships. The definition may vary depending on the context and jurisdiction, and it often implies a level of mutual support and shared responsibilities.