What do you call unionists who agree to discuss the unification of Ireland? Well, for a start, you don't call them unionists, no more than you would call Mary Lou McDonald a monarchist. Other analogies are available.
And this tells you the simple reason why unionists currently baulk at entering talks with others on how the island can be reframed as a single jurisdiction outside the United Kingdom.
Some will argue that unionists should involve themselves in the discussion, because there are advantages to be gained, given the share of the vote they would be able to command in the new state. These "advantages" would be viewed by unionists as the terms of their surrender.
Arlene Foster condemns the presumption of many nationalists that a united Ireland is 'inevitable'.
It comes easy to nationalists to imagine that partition is simply a violation of an island nation; that it was a temporary measure, which is already obsolete.
Sammy Wilson tells us that the current arrangements have endured for a century and that we can thrive under them for yet another hundred years. Well, only if a majority here wants to.
Unionists have to live with the embarrassing reality that their state can not rouse much interest in marking its own centenary.
No one seems very confidant now that Theresa May's promised Festival of the Union will go ahead as promised next year, this despite the fact that we now have at Westminster a Minister of the Union. That office was created by, and is currently held by, Boris Johnson, but not even the most ardent member of the DUP would invest hope in anything he says.
So, what should unionists do when the expectation is growing, however unrealistically, that Ireland will be united and soon?
Their current strategy seems to be to exclude themselves from the conversation; to act as if nothing has changed to make a united Ireland more likely and, presumably, allow this embarrassingly unproductive anniversary to pass in the hopes that the conversation will change next year. But many things have changed already and unionism, if it is to survive, must pitch for the Union. The section of the population that used to be called "the minority" is no longer in the minority. The traditional "majority" is no longer a majority.
The state was established to give stability to that British-identifying community and protect it against being absorbed into a united Ireland.
But if the old plan to secure territory through a managed demography has expired, what's the new plan?
Fortunately, for unionists, they do have some advantages, even in the changed balance of communities.
A growing number of people do not wish to identify as either nationalist or unionist and these people may not wish to vote for a united Ireland.
Currently, these people, however, are probably not voting for the DUP. They have, in the main, emerged from a liberal, secular tendency that despises the DUP.
This suggests a horrifying prospect for the DUP: that it might actually be an obstacle to preserving the Union; that it might serve the Union better by backing off, or at least winding down its more abrasive evangelicalism, conservatism and monarchism.
Otherwise, many of these secular liberals who don't care whether they are regarded as Irish or British might decide that they would be more comfortable in a liberal, secular united Ireland than in a claustrophobic Northern Ireland which is perpetually bickering about those very liberal concerns that do matter to these people.
So, my advice to unionists? Some are doing quite well. Robin Swann and Doug Beattie are managing to impress across the divide. No one needs to pull us out of the UK to escape from people like them. The nature of the argument for a united Ireland has changed. The Ireland envisaged is not the Ireland of De Valera, Cathal Goulding, the young Gerry Adams, or Archbishop McQuaid.
It is a place in which people have moved out from under the shadow of restrictive religion and chauvinistic readings of history. The best counter to a need for that kind of new all-Ireland state is to make Northern Ireland as genial as possible a place in which to live and to be Irish or British. Unionism has to change.
That's not to say that there won't always be many people in Northern Ireland who would vote for a truculent and evangelically motivated DUP.
It is just to say that, in doing so, those people will not be assisting in creating the kind of society that will be happy to remain part of Britain.
The irony for the DUP is that its project to preserve the Union is not the same as its project to preserve the party.
They may take some comfort from the same reality applying to Sinn Fein. Celebrating the IRA is not going to woo young liberals away from the Alliance Party. And those young liberals might be thinking that the last kind of united Ireland they would want to be part of is one in which Sinn Fein is in government.
Ironically, the issue of Irish unity will be decided by those who care least, one way or the other. Well, that's democracy for you. Unionism has to pause and recognise that making this place more secular and liberal and more Irish may be the best way to persuade post-Protestant Ulster to leave an intangible border alone.
Of course, there is the additional problem of the changing character of the UK, with Scotland set to leave and, for the meantime, a shifty mountebank as Prime Minister. I wouldn't worry about polls that ask people how they would vote today when they have no idea today what the offer will be.
Unionists should worry about how the next 10 years will change this place and change the Republic and change Britain and accept that you have very little control over any of this.
Then they should make what little difference they can by working against sectarianism and division.
And perhaps if they made their presence felt in the Republic, to undermine nationalist arguments that the north is a failed entity, or an uncomfortable place for those who identify as Irish, then people there, faced with a vote, might vote to leave things here as they are.
But first unionists need to acknowledge that a debate has started about the shape of a future Ireland and they need to engage with it.