1. The latest dictionaries define marriage as "the social institution under which a man and a woman establish their decision to live as husband and wife by legal commitments, religious ceremonies, etc."
2. Marriage is an agreement (a covenant) between two eligible parties, to take each other in holy matrimony, according to the laws of God and the laws of the land, providing the laws of the land do not contradict God's will.
3. Since marriage in also a civil contract, I want to call your attention to another definition of it. "Marriage is a covenant, contract, civil, spiritual, and moral, establishing a permanent union between a man and a woman, involving mutual responsibilities that cannot be terminated at the will of one or both." This puts marriage in its proper perspective, showing that it is a permanent union between a man and a woman, in establishing a home and that it involves mutual responsibilities which cannot be terminated at the whim or fancy of one or both of the parties.
4. Genesis puts the biblical meaning of marriage very plainly:

Genesis 2:18, 23-24 (vs. 18) And the Lord God, said, It is not good that the man should be alone; I will make him an help meet for him. (Vs. 23-24) And Adam said this is now bone of my bones, and flesh of my flesh; she shall be called woman, because she was taken out of man. Therefore, shall a man leave his father and his mother, and shall cleave unto his wife; and they shall be one flesh.

Marriage is a Divine Institution. God established marriage as an institution in the garden of Eden. He made the man(Adam) from the dust of the ground, and then from man's side God took a rib out of which the body of the woman(Eve) was formed. God presented the woman unto the man and they were pronounced "one flesh" (Gen. 2:18-24). The Bible plainly affirms that it was God's intention that there would be one man and one woman - male and female - in marriage throughout time. Matt 19:4-6:

Marriage is God's pattern for Oneness. Since it is impossible for man to direct his own steps (Jer. 10:23); God has supplied sufficient help in His Word in respect to marriage.

Marriage in Monogamic in form. A person can have only one scriptural mate at a time. I Cor. 7:2 Nevertheless, to avoid fornication, let every man have his own wife, let every woman have her own husband.

Marriage is Mutual in Obligation. Man and woman are complements of each other and dependant upon each other. Whereas the wife must fear her husband, he is commanded to love his wife "each as Christ loved the church." (Eph. 5:25) "Husbands love your wives, even as Christ also loved the church, and gave himself for it."

They are mutual in Love - (Eph. 5:28) "So ought men to love their wives as their own bodies. He that loveth his wife loveth himself."

In Gratification - (I Cor. 7:3-5) "Let the husband render unto the wife due benevolence: and likewise also the wife unto the husband. The wife hath not power of her own body, but the husband and likewise also the husband hath no power of his own body, but the wife. Defraud ye not the other, except it be with consent for a time that ye may give yourselves to fasting and prayer; and come together agan, that Satan tempt you not for you inconstinency."

In Procreation - (Titus 2:4-5) "That they may teach the young women to be sober, to love their husbands, to love their children, to be discreet, chaste keepers at home, good, obedient to their own husbands, that the word of God be not blasphemed."

She is to submit unto her own husband - (I Peter 3:1) "Likewise, ye wives, be in subjection to your husbands; that, if any obey not the word, they also may without the word be won by the conversation of the wives".

Marriage is Indissoluble in Nature. This was taught from the beginning. (Gen. 2:24; Matt. 19:6). In God's sight the marriage contract is final until broken by death or infidelity. (Rom. 7:2-3) "For the woman which hath an husband is bound by the law to her husband so long as he liveth; but if the husband be dead, she is loosed from the law of her husband. So then, if while her husband liveth, she be married to another man, she shall be called an adulteress: but if her husband be dead, she is free from that law; so that she is no adulteress, though she be married to another man". (Matt. 19:9) "And I say unto you, whosoever shall put away his wife, except it be for fornication, and shall marry another, committeth adultery; and whoso marrieth her which is put away doth commit adultery".

Marriage is Honorable in All. (Heb. 13:4) "Marriage is honorable in all, and the bed undefiled, but whoremongers and adulterers God will judge". (Prov. 18:22) Whoso findeth a wife findeth a good thing, and obtaineth favor of the lord".