Common-law Marriage (Noun)

A marriage relationship created by agreement and cohabitation rather than by ceremony.

Nouns denoting natural processes.

They lived together for many years and considered themselves to be in a common-law marriage, despite never having had a formal wedding ceremony.
In some states, a common-law marriage is recognized as a valid marriage, with the same rights and responsibilities as a traditional marriage.
The couple had been together for over a decade and had two children, but they had never formalized their relationship through a common-law marriage or any other type of ceremony.
After many years of living together, the couple decided to formalize their common-law marriage by getting married in a small ceremony.
In the eyes of the law, a common-law marriage is just as binding as a traditional marriage, with the same legal rights and responsibilities.