A more thorough explanation:

Definition: Matrimonium (ma-truh-moh-nee-uhm) is a Latin term used in Roman law to refer to marriage. It is also known as nuptiae (nuhp-shee-ee). Matrimonium ipsum (ma-truh-moh-nee-uhm ip-suhm) is a historical term that refers to marriage itself.

• Under Roman law, matrimonium was a legal contract between a man and a woman that established their rights and obligations as spouses.
• In ancient Rome, matrimonium was considered a sacred institution that was essential for the continuation of society.
• Matrimonium ipsum was often celebrated with elaborate ceremonies and feasts, and was seen as a way to unite families and create alliances between them.

These examples illustrate how matrimonium was an important concept in Roman society, and how it was viewed as a fundamental institution that played a crucial role in the social and political life of the time.