Marriage is the coupling of two adults; that is, marriage is a relationship of monogamous copulation. That is why marriage is the union of a man and a woman for life. Two men or two women cannot copulate together. More than two adults cannot be monogamous.
A marriage begins when it is consummated, which means the bride and groom copulate. If the consummation cannot take place, as for instance because of a physical deformity, the marriage cannot begin. Only adults who can copulate together can be married.
Marriage is a social institution, which is normally recognized by the government, though some people forgo such recognition. It can happen that the government will recognize relationships as marriage that society as a whole does not recognize. For example, the (Roman) Catholic Church has standards for divorce and annulment of marriage which differ from that of the government.
That is also the situation of society today concerning “same-sex marriages”. The government recognizes these but both the Catholic Church and many non-Catholics do not recognize them as marriages. Society and the government have different definitions of marriage.
We have seen in the 20th century how governments can attempt to redefine language. Totalitarian governments seek to make it impossible to think thoughts they find dangerous. George Orwell satifized this in what he called Newspeak. Forced labor camp was “joycamp”. Compliance to Party orthodoxy was “plusgood”. “Thoughtcrime” was the criminal act of holding politically incorrect beliefs or doubts.
“Compelled speech” is a legal term with wider connotations. It means the state is compelling individuals or corporations to speak, or to speak in a prescribed manner. There are cases in which it is consistent with democratic principles, such as requiring warnings on packages of cigarettes. However, when speech is compelled concerning controversial matters of society, it is coercive and against democratic principles.
For example, the state of California passed a law to force pro-life pregnancy centers centers to speak a message that directly contradicts their beliefs and mission. The Supreme Court struck down this law. Their ruling “makes it clear that no one should be forced by the government to express a message that violates their convictions, especially on deeply divisive subjects such as abortion.” (adflegal.org)
The definition of marriage is another such an issue. The question is to what extent the government can force people to speak a language that re-defines marriage as something other than what they believe it is. Such compelled speech should be forbidden in a democratic society, and people should be allowed to speak a language they understand and that reflects their beliefs about a basic institution of society, marriage.