The cool and crummy thing about language (American English in particular) is that it can be fluid.
Language is really just sounds that we put together in unique ways and assign meaning. And written language is just a way to represent those sounds... without making any sound...
I say that word, and you have an image in your mind.
That one might have a couple possibilities. Without some context, you may be visualizing a spherical object, or you might be seeing people dancing.
Same sound, different spellings, different meanings.
Meanings can change over time as well. "He was a killer", "That's killer".
I think part of the problem with this word is that it means several different things. There are several flavors and contexts. I thought I'd take a stab at listing them. The idea is to break it up into the various separable components.
Social-Contractual - In this context, marriage is a contract between two or more people to "bind their fortunes". They agree to combine their resources toward a set of common goals. Often, but not always this includes the creation and rearing of offspring for a number of purposes, including contributing to society, maintaining a family namesake and/or legacy...
Social-Emotional - (That may not be the right title, suggestions?) In This context marriage is a... celebration of a union, of one or more... things? I am trying to leave that as open as possible to account for all cases, Such as a Man who married his dog, or a nine year old who was married to a snake (symbolically. She will still get to marry someone else when she grows up).
Civil-Legal Blanket -(Again, not sure I love the title) This represents a contract recognized by society as a sort of master contract, which saves the paperwork required to establish joint property ownership, inheritance, access to "Family" benefits etc...
Civil-Incentive - This represents a union which gains access to benefits created by the governmental unit: This would be things like child tax credits. This facet exists primarily because governments want to encourage population growth and/or child rearing activities. So they reward people for participation in the Social-Contractual facet of marriage.
Civil-Regulatory - This represents a level of governmental oversight of marriage. An example: In the early days of the United States, marriage was often a case of two people moving in together and declaring themselves married (There are still laws in some states, which establish a time frame after which cohabitation is automatically recognized as marriage after a certain duration). Then at some point, some states decided to regulate the process. Most of what I have read indicates this was sometime after the Civil war, with differing reasons given, the most common being to prevent interracial coupling, and cousin coupling.
Commercial - This facet refers to the industry built around the term "Marriage"; The dresses and tuxedoes and parties and cakes etc... It is most closely tied with the Social-Emotional aspect.But really no different than any other commercialized holiday. It is a group of industries encouraging or creating a need for their products.
Religious - This represents a contract between deity and two or more individuals. It is defined by the specific religious practice selected by the individuals. Typically in involves an agreement to set aside personal individualism in favor of familial collectivism. The join their purposes and wills together, along with that of their respective deity in accordance with laws and guidelines established by that deity.
Did I miss any?
While there are points where each of these touch one another or overlap slightly, they are in fact separable.
Do you suppose, if each had a unique name, much of current political strife could/would have ben avoided?