The words "husband" and "wife" are to be removed from official documents under the Coalition's plans to reform the laws around same-sex marriage.
Immigration, tax and benefits forms would be redesigned to remove the terms that imply that a marriage is between a man and a woman. The words "bride" and "bridegroom" could also be axed from marriage certificates.
The possible changes were highlighted in Thursday’s Consultation Paper on Equal Civil Marriage unveiled by Home Secretary Theresa May and Equalities Minister Lynne Featherstone.
On Friday, the Church of England offered its first official statement on the issue, reiterating its position on a "traditional understanding" of marriage as an institution between "one man and one woman”.
“Opening marriage to same sex couples would confer few if any new legal rights on the part of those already in a civil partnership, yet would require multiple changes to law, with the definition of marriage having to change for everyone,” said a church statement.
“The issue of whether marriage should be redefined to include those of the same sex is a more complicated picture than has been painted,” it added.
The Coalition’s push towards allowing gay and lesbian couples to take part in civil marriage has been a theme of the Cameron’s tenure, with the prime minister championing reform in his party conference speech, declaring: "I don't support gay marriage despite being a Conservative. I support gay marriage because I'm a Conservative."
On Thursday, Featherstone echoed Cameron, insisting that marriage is "a celebration of love and should be open to everyone".
The government’s plans are expected to be in place by 2015, at a cost of around £4m.
Under the plans put out for consultation, same-sex couples will be entitled to get married in a register office or other civil ceremonies, or convert existing civil partnerships.
Opponents of the reforms have been vocal, particularly religious leaders who have attacked the government for what they call a misunderstanding of the "essence of marriage”.
On Friday, the Archbishop of Westminster, the Most Reverent Vincent Nichols, reiterated his belief that marriage can only be between a man and a woman.
Speaking on the BBC’s Newsnight, Nichols was asked for his response were a catholic gay couple to ask him to marry in the church.
"I would want to say to them that I understand their desires, that I understand their experience of love is vitally important in their lives, but I would want to say to them that they are called in my view, in the church's view, to a very profound friendship in life,” he said.
"Marriage is about bringing difference together. Different sexes, sometimes different families, different tribes. It's been used to bring kingdoms together. It's about bringing difference together, out of which comes a new start and a new life.
"The gender difference is essential for its creativity and its complementarity."
He added that he thought it was not a good idea to “change, to shake, that fundamental idea of marriage in which a man and a woman call each other husband and wife."
In response, Home Office minister Nick Herbert accused the Archbishop trying to “dictate the institution of civil marriage outside of his church which is not a matter for the church.”
"The idea that we can rest on this issue is wrong,” said Herbert. “Symbolically, as well as the merits itself, I think it incredibly important that as a society we say the valuable institution of civil marriage is available to all.”
According to the consultation paper, the reforms will include a separate category – religious marriage – that will be reserved only for a man and a woman.
Instead of the gender specific terms husband and wife, official forms will feature the words partners or spouses.
The changes, which would affect England and Wales, were backed by the Family and Parenting Institute charity.
Chief executive Katherine Rake said: "As a society we need to do all that we can to support stable couple relationships. Stability is vital for the well-being of children. The wider members of a family around the couple also benefit.
"It's important for UK society to offer all couples a genuine choice on how they can best achieve this stability. Gay couples should be allowed to choose civil marriage if they decide it's the best option for them."
But the consultation was dubbed a "sham" by the Coalition for Marriage (C4M), which counts several Tory and Labour MPs and a number of Church of England bishops among more than 200,000 signatories to an online petition.
Campaign director Colin Hart said: "This consultation is a sham. It is being pushed through despite the public never having a say on this change. None of the main political parties proposed redefining marriage in their manifestos and the impact assessment misses out many of the possible problems that could occur if this institution is redefined. For example, how this change will affect our schools.
"C4M and the 200,000 people who have signed our petition believe that this change is profoundly undemocratic, will have massive consequences for society and is simply unnecessary as civil partnerships provide all the legal rights of marriage."
UK Independence Party spokesman David Coburn said: "It seems that through some kind of political correctness, David Cameron is picking a fight with the millions of people whose religious faiths do not recognise same-sex marriages.
"That, in our view, is an aggressive attack on people of faith and an act of intolerance in itself. This is a concern that must be expressed in the consultation."
The impact assessment published alongside the consultation puts the cost of the change, mainly in terms of changing IT systems and staff training, at up to £4.5 million.
It noted that after an initial flurry, the number of civil partnerships being entered has steadied at around 58,000 per year, with between 68,000 and 88,000 now in place.
One advantage of the new system would be allowing same-sex couples to keep their sexuality hidden. At present, being in a civil partnership automatically signifies a couple is gay.
Wedding venues such as hotels would be able to carry out same-sex civil ceremonies under their existing licences, the assessment suggested.
One Tory MP opposed to the change suggested it would open the door to other claims, such as legalising Islamic marriages involving multiple wives.
Julian Brazier, who opposed the introduction of civil partnerships, said he did not have a problem "with people forming these relationships".
But he told BBC Radio 4's The World At One: "If we are going to say to the gay lobby that we are going to revise, completely change, this definition from one man and one women, what do we then say to the much larger group of Islamic people in this country?
"They have, in sharia marriage, up to four wives. Why are we making a change for one group but refusing it to a larger group?"
Advocates of civil partnerships had insisted at the time that they were not a first step to same-sex marriage, he pointed out.
"It, of course, within seven years has turned into exactly that.
"I do not have a problem with people forming these relationships. I do not have a problem with changes in the law to reflect the international problems.
"But it seems to me that the institution of marriage, which has been with us for more than 2,000 years, is fundamental."
Tory MPs had "a free vote and a variety of different views", he said, denying the issue was a clash between the two sides of the coalition.
Tory MP Peter Bone said he "threw up" when the Prime Minister told his party he supported gay marriage "because" he was a Conservative.
He told Ian Payne on LBC 97.3: "I threw up when I heard that comment. It was at the party conference and on what authority he had to say that, I do not know and that's why, if you listen to what he said, he's making that a party political thing.
"It's saying you have to vote for gay marriage because you're a Conservative. There is absolutely no basis whatsoever for saying that.
"He can, of course, support gay marriage if that's what he believes in, but he can't pretend this is Conservative policy, tradition or anything.
"The Prime Minister is doing a lot of good things for the country but on this particular issue, he is totally and utterly wrong."
On Thursday, it was reported that Tory MPs opposed to gay marriage will not be forced to vote in favour of the plans.
Cabinet Office minister Francis Maude told the Daily Telegraph that Conservative MPs would not be whipped to vote in favour of the legislation when it comes before Parliament.
In February, MPs, peers and religious leaders launched a petition in an attempt to block government plans to "redefine" marriage to allow gay couples to tie the knot.
"Primarily I am supporting it as a mother, as well as an MP, because research shows over different cultures and different ages that children flourish when they are brought up in a secure family environment, and this traditionally has been marriage," she said.