Marriage doesn't need to be redefined.
matrimonium is an institution involving a mother, mater. The idea implicit in the word is that a man takes a woman in marriage, in matrimonium ducere, so that he may have children by her."
http://en.wikipedia.org/wiki/Same-sex_marriage
Webster's New International Dictionary, Second Edition, defines marriage as follows:
"A state of being married, or being united to a person or persons of the opposite sex as husband or wife; also, the mutual relation of husband and wife; wedlock; abstractly, the institution whereby men and women are joined in a special kind of social and legal dependence, for the purpose of founding and maintaining a family."
The Century Dictionary and Encyclopedia defines marriage as:
"The legal union of a man with a woman for life; the state or condition of being married; the legal relation of spouses to each other; wedlock; the formal declaration or contract by which a man and a woman join in wedlock."
Black's Law Dictionary, Fourth Edition, defines marriage as:
"The civil status, condition or relation of one man and one woman united in law for life, for the discharge to each other and the community of the duties legally incumbent upon those whose association is founded on the distinction of sex."
In substance, the relationship proposed by the appellants does not authorize the issuance of a marriage license because what they propose is not a marriage.
http://ky.findacase.com/research/wfrmDocViewer.aspx/xq/fac.\SAC\KY\1973\19731109_0040029.KY.htm/qx