The
definition does not, it is just a description of what the word is used to mean. But
a priori anyone is free to do anything, unless you have a good reason why they should not be allowed to do so.
So if you want to say that people are not free to marry someone of a given [race/sex] you need to justify this restriction to the rest of society or we are going to tell you to mind your own business and leave the [same sex/interracial] couples to get on with
their lives.
No, while any word
could mean anything
in principle, ‘marriage’ means the same thing it has since Roman times - a civil legal arrangement covering two (or more) people who are coming together to form a new family unit. And in roman history it was even used several times explicitly to refer to same sex couples.
Now if
you want to use it in a more restrictive religious sense, feel free. If you want to come up with a new word, copyright (or whatever the appropriate intellectual property term would be) it, use that in a more restrictive sense and prevent the nasty homosexuals from using it, feel free.
But if you want to seize ownership of the preexisting word ‘marriage’, tell the rest of us that we may only use it as you dictate, and prevent the nasty homosexuals from using it, then no. Indeed

no.
Great, feel away. Let me know how that works out for you.
Your problem is that you need the assent of people like me to force your will on the homosexuals. If push comes to shove we can just shrug and ignore you. Even the majority of ‘Catholics’ disagree with you.
So a hardline dogmatic line of repeating your opinion and making no attempt to engage with the other side is a tactically disastrous approach for you.
I only referred to sexual
preference - where there are plenty of examples of homosexual preference in nature.
You are the one who referred to “the natural definition of marriage”, so yes do please find me some examples of animals getting
married in nature.