http://en.wikipedia.org/wiki/Marriage#Etymology 
The word "marriage" derives from Middle English mariage, which first appears in 1250–1300 CE This in turn is derived from Old French marier (to marry) and ultimately Latin marītāre meaning to provide with a husband or wife and marītāri meaning to get married. (The adjective marīt-us -a, -um meaning matrimonial or nuptial could also be used in the masculine form as a noun for "husband" and in the feminine form for "wife."[13]
The related word "matrimony" derives from the Old French word matremoine which appears around 1300 CE and ultimately derives from Latin mātrimōnium which combines the two concepts mater meaning "mother" and the suffix -monium signifying "action, state, or condition." "[14]E' essenzialmente una questione linguistica, si tratta di parole derivate e composte che sono state crate con dei precisi significati e un senso ben definito:
Quindi matrimonio ha un senso ben preciso tra un maschio ed una femmina e non ha alcun senso applicato all' unione omosessuale
**Modificato dall'autore il 19.08.2012 20:35**