common-law marriage   n.  A marriage existing by mutual agreement between a man and a woman, or by the fact of their cohabitation, without a civil or religious ceremony.

common-law marriage

A legal marriage brought about by the cohabitation of a man and a woman, or by their agreement to consider themselves married, rather than by a wedding. (See common law.)

Main Entry: common–law marriage
Function: noun
: a marriage that is without a ceremony and is based on the parties' agreement to consider themselves married and usually also on their cohabitation for a period and their public recognition of the marriage —compare CONCUBINAGE
NOTE: Most jurisdictions no longer allow this type of marriage to be formed, although they may recognize such marriages formed prior to a certain date or formed in a jurisdiction that does permit common-law marriages.