From dictionary.com I particularly like #4.
mar·riage
[mar-ij] noun
1.the social institution under which a man and woman establish their decision to live as husband and wife by legal commitments, religious ceremonies, etc.
2.the state, condition, or relationship of being married; wedlock: a happy marriage.
3.the legal or religious ceremony that formalizes the decision of a man and woman to live as husband and wife, including the accompanying social festivities: to officiate at a marriage.
4.a relationship in which two people have pledged themselves to each other in the manner of a husband and wife, without legal sanction: trial marriage; homosexual marriage.
5.any close or intimate association or union: the marriage of words and music in a hit song.
6.a formal agreement between two companies or enterprises to combine operations, resources, etc., for mutual benefit; merger.
7.a blending or matching of different elements or components: The new lipstick is a beautiful marriage of fragrance and texture.
8.Cards. a meld of the king and queen of a suit, as in pinochle. Compare royal marriage.
9.a piece of antique furniture assembled from components of two or more authentic pieces.
10.Obsolete. the formal declaration or contract by which act a man and a woman join in wedlock.
