I did a google search for "define:marriage" and this is the list it came up with.
(Some links didn't highlight...not sure why

)
Definitions of marriage on the Web:
* the state of being a married couple voluntarily joined for life (or until divorce); "a long and happy marriage"; "God bless this union"
* two people who are married to each other; "his second marriage was happier than the first"; "a married couple without love"
* the act of marrying; the nuptial ceremony; "their marriage was conducted in the chapel"
* a close and intimate union; "the marriage of music and dance"; "a marriage of ideas"
www.cogsci.princeton.edu/cgi-bin/webwn
* Marriage is a relationship and bond, most commonly between a man and a woman, that plays a key role in the definition of many families. Precise definitions vary historically and between and within cultures, but it has been an important concept as a socially sanctioned bond in a sexual relationship. Globally, societies that sanction polygamy as a form of marriage are far more common than those that do not. However, monogamy is overwhelmingly most widely practiced, followed by polygyny, with othe
en.wikipedia.org/wiki/Marriage
* The state-recognized, voluntary and exclusive contract for the lifelong union of two persons. Most countries do not recognize marriage between same-sex couples or polygamous marriages.
www.duhaime.org/dictionary/dict-m.aspx
* was instituted in Paradise when man was in innocence (Gen. 2:18-24). Here we have its original charter, which was confirmed by our Lord, as the basis on which all regulations are to be framed (Matt. 19:4, 5). It is evident that monogamy was the original law of marriage (Matt. 19:5; 1 Cor. 6:16). This law was violated in after times, when corrupt usages began to be introduced (Gen. 4:19; 6:2). We meet with the prevalence of polygamy and concubinage in the patriarchal age (Gen. 16:1-4; 22:21-24; 28:8, 9
christianity.about.com/library/weekly/blT0002400.htm
* Feudal right to arrange marriage of widow or ward. (Sayles, George O. The King's Parliament of England, 145) Related terms: Merchet
www.netserf.org/Glossary/m.cfm
* Until very recent times New York followed the common law respecting marriage. All that was required for a valid marriage was the deliberate consent of competent parties entering into a present agreement. No ceremony or intervention of a civil authority was necessary.
www.newadvent.org/cathen/11029a.htm
* The act of uniting a man and woman for life... Marriage was instituted by God himself. . . . "Marriage is honorable in all. . . ." Heb. 13. Marriage: ...men and woman are joined in a special kind of social and legal dependence for the purpose of founding and maintaining a family. . . an intimate or close union
www.face.net/Webster's_1828.html
* the ceremony of union of man and wife was a sacrament of the church
medievalwriting.50megs.com/churchglossary/glossaryi.htm
* A contractually committed partnership, including sexualove, cohabitation, shared economy/property and mutual childrearing.
www.number-one-adult-sexual-health-terms-advisor.com/relationshipstyles.htm
* Historically, a relationship between a male, a female and their families whose primary purpose is to raise offspring. Today many people use the word to describe a committed, loving relationship with or without children.
www.familysynergy.org/art-poly.html
* A permanent and exclusive partnership of a man and woman for their whole lives for the good of both spouses and for the procreation and education of children
www.gidiocese.org/tribunal/terms.htm
* * Age-specific first marriage rates For men (or women), the age-specific first marriages rates are obtained by dividing the number of first marriages of men (or women) of a given age by the number of never married men (or women) in the same age at June 30.
www.aifs.gov.au/institute/info/charts/glossary.html
* An alternative name for the Beatitude, the fourth stage of the after-life, conceived of as the symbolic marriage of the Spirit and the Celestial Body.
www.yeatsvision.com/Terminology.html
* (1) Julia Thorne, divorced (2) Teresa Heinz Kerry
www.localcolorart.com/search/encyclopedia/John_Kerry/
* A covenant or partnership of life between a man and woman, which is ordered to the well-being of the spouses and to the procreation and upbringing of children. When validly contracted between two baptized people, marriage is a sacrament (Matrimony).
www.thesacredheart.com/dictnary.htm
* The state or condition of a community consisting of a master, a mistress and two slaves, making in all, two.
www.onelang.com/encyclopedia/index.php/The_Devil's_Dictionary
* The legal union of a man and a woman which establishes their relationship as husband and wife. See Code of Alabama for additional information. Marriage data are reported by the county where the marriage occurred.
ph.state.al.us/csc/vs/Help/Dthstatrel1/Definitions.htm
* A set of cultural rules for bringing men and women together to create a family unit and for defining their behavior toward one another, their children, and society.
highered.mcgraw-hill.com/sites/0072549238/student_view0/glossary.html
* is the act, ceremony or process by which the legal relationship of husband and wife is constituted. The legality of the union may be established by civil, religious, or other means as recognized by the laws of each country.
twig.sdsu.edu/demoybk/technote/english/glossary.htm
* Area: Human Cognition and Emotion Text Pages (est.): 5 Joanne Davila State University of New York at Buffalo
208.164.121.55/reference/STRS/strestoc.htm
* a special contract of permanent union between a man and a woman entered into in accordance with the law for the establishment of conjugal and family life. It is the foundation of the family and an inviolable social institution whose nature, consequences, and incidents are governed by law and not subject to stipulation, except that marriage settlements may fix the property relations during marriage within the limits provided by the Family Code of the Philippines.
www.nscb.gov.ph/ru12/DEFINE/DEF-POP.HTM
* The socially recognised union of man and woman, especially to give status to their children. Western-style official marriage stems from Judaic ecclesiastical law and its belief that sex should be confined to inside marriage. The Romans and other Western peoples never held any wedding ceremony; marriage began by the couple moving in together, while divorce was carried out by the breaking of a pot or public proclamation. Martin Luther believed marriage should be a social decision and not one taken by the church, thus he also allowed divorce while the Catholic Church didn't.
www.embassy.org.nz/encycl/m2aencyc.htm
* The Mormon Church teaches two types of marriage. One ends at death. The other is for "time and eternity." If the couple is married in a Mormon temple by someone with authority it is believed they will stay married in the next life. This kind of marriage is needed if they are to progress, not only as husband and wife, but as God and Goddess.
roblundberg_docs.tripod.com/mormon_terminology.html
* a more or less stable union, usually between two people, who are likely, but not necessarily, to be co-resident, sexually involved with each other, and procreative with each other.
www.geocities.com/brianmyhre/8Def.htm
* (1) Julia Thorne, divorced (in civil law, annulled in Roman Catholic Canon Law) (2) Teresa Heinz Kerry
encyclopedia.laborlawtalk.com/John_Kerry
* Prior to 2003, marriage was defined as the legal conjugal union of two persons of the opposite sex. Since 2003, the definition of marriage has been changed in some provinces and territories to include the legal conjugal union of two persons of the same sex. Common-law relationships are excluded.
www.statcan.ca/english/freepub/84F0212XIE/2002/definitions.htm
* le mariage
www.happychild.org.uk/freeway/french/vocab/family06.htm
Cited from:
http://www.google.com/search?hl=en&...a:en-US:official&oi=defmore&q=define:marriage
My personal opinion is that a marriage is a declaration of love and committment between two people before God to honor eachother and live for the Lord. I am sure I could get more specific, but this is a pretty elaborate question...