Merriam-Webster online says:
(1): the state of being united to a person of the opposite sex as husband or wife in a consensual and contractual relationship recognized by law
(2) : the state of being united to a person of the same sex in a relationship like that of a traditional marriage
(marriage: b: the mutual relation of married persons"
Strongs says:
(In the Old Testament, `ownah {o-naw'}.
1) cohabitation, conjugal rights
(In the New Testament, gamos {gam'-os}
1) a wedding or marriage festival, a wedding banquet, a wedding feast
2) marriage, matrimony
What are the Biblical requirements for considering oneself to be "married"? (What does the Bible say?)
1) Marriage is God's invention
Genesis 2:18 "Then the LORD God said, "It is not good that the man should be alone; I will make him a helper fit for him."
2) Marriage means to leave and hold fast
Genesis 2:24 "Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh."
3) Marriage is a covenant - and God is the witness.
Malachi 2:14 "But you say, "Why does he not?" Because the LORD was witness between you and the wife of your youth, to whom you have been faithless, though she is your companion and your wife by covenant."
4) Marriage is a relationship that is recognized and/or regulated by law.
Romans 13:1 "Let every person be subject to the governing authorities." Unless we have a real reason to believe that the state is asking us to sin by following the law in order to be married, we must obey the laws of the land.
5) Marriage is a reflection of God and His people. In the Old Testament, the people were Israel, in the New Testament, it is the church. As Paul wrote, this is a mystery.
What do you have to DO to be "married"?
Do you need to have a ceremony? No - the Bible never says that there must be a ceremony in order to be married in the eyes of God. Marriage is an life-long agreement between a man and a woman.
Do you need to be married by a minister? No - the Bible never says that.
Does marriage belong to the church? No - God created marriage to be a life-long agreement between a man and a woman and virtually all societies have had marriages of one sort or another. The Bible does not say that marriage belongs to the church.
What about traditions?
They are traditions - and some very nice ones, too. But they are only traditions. The wedding traditions of the ancient world were very different from our traditions today. But their marriages were just as much marriages then as ours are today. Nearly every society marks the beginning of a marriage with a ceremony or rite, but it is not necessary, except to our human minds.
God and His Word clearly tell us that marriage is designed to be for life. A man and a woman in a covenantal arrangement, with God as the witness.