Having argued that we may legitimately use the term 'Traditionalism' and its cognates (Traditionalist etc.) I should say what I think it means.
The best definition I've heard is this (from Fr James McLucas, formerly editor of the The Latin Mass Magazine): from memory,
A Traditionalist is a Catholic who wishes to live in organic continuity with previous generations of Catholics.
Given the huge changes in the Church over the last half century such a desire, if it is serious, implies a serious and sustained effort. In the past much less effort, if any, was required of ordinary Catholics to live in organic continuity with previous generations of Catholics. And everyone could be assumed to want to live like that.
The most obvious application of this desire is in the liturgy. The Novus Ordo Missae promulgated in 1969 is in organic continuity with previous editions, and the broad liturgical tradition, only in a sense which is thinner, more attenuated, than the sense in which the Missal of 1962, or the Missal of Trent, or any other pre-62 edition, is in organic continuity with its predecessors. I think I can say that without fear of contradiction. The Holy Father has made this point more forcefully but I will leave it at that. Saying just this explains why Traditionalists are 'attached to the previous liturgical tradition', as it is sometimes expressed (in the Motu Proprio, for example).
The Traditionalist attitude towards continuity with the past has other implications. Rubricarius says we have something in common with the liberals. True: like them we reject Ultramontanism, the position which emphasises Papal authority (or more broadly the authority of the Holy See) over other sources of authority and information, such as Scripture, Tradition, and Councils.
As I see it Liberalism replaces Ultramontanism with an inconsistent view of what we should take most seriously as Catholics. It places Vatican II at the heart of things; yet VII only has authority as a General Council, so it is inconsistent to emphasise VII at the expense of other Geneal Councils. Using (one interpretation of) VII to reject VI and Trent, for example, just doesn't make sense.
Liberals and Conservatives have something in common, it seems to me: a disinclination to make distinctions between different levels of authority in post-conciliar Church statements. Liberals reject them all (as they see fit) without distinctioin, and Conservatives regard them all as equally binding.
This is broad-brush stuff. But I've noticed Conservatives get very impatient with Trads when we point out, for example, that various positions are merely the private opinions of recent Popes, or have not been properly promulgated, or only come from a dicastery etc.. Of course this impatience follows from Ultramontanism.
Like many trads I used to be a Conservative, so when I talk about or criticise Conservativism I am in part talking about my own former self. I can see now that I used to want to live in organic continuity with previous generations of Catholics, but within the limts set by Ultramontanism. So, because this or that had been approved (note: approved, not declared infallible) by recent Popes, I thought I ought to go along with it. When I finally saw the error of Ultramontanism, my traditionalist instinct was able to develop more fully.
The error of Ultramontanism is easy to see, with hindsight, because it is rejected not only by Liberals and Trads but also by the Pope and the Papal Magisterium. In the chaotic decades which have followed the Council, Papal teaching has often been a lifeline for Catholics who wanted to see traditional teachings reiterated; it is natural that Conservatives have clung on to it. It is understandable, but obviously wrong, to take this to an extreme and start saying that whatever the Pope, or some Vatican department, makes a friendly off-the-cuff remark about must be imposed on everyone by next Tuesday, and the Popes themselves would regard this attitude as absurd.
Hence we find a frequent contrast between what Popes have said about their own positions, and how Conservatives have applied those positions. So Paul VI said that Natural Family Planning can be legitimate in certain circumstances. And you get Catholics who regard themselves as Conservative saying that all Catholics preparing for marriage should be drilled in it. John-Paul II said that the Luminous Mysteries of the Rosary might be found helpful, and Conservative presses suddenly pulp all their books on the Rosary so they could add the new mysteries, and conservative parishes insist on having them. Benedict XVI carefully explains that his books are not papal teaching, but his opinions as a private doctor, but Conservatives promote them without such a warning and they are printed wrapped in the papal colours.
I'm not saying these applications are wrong. But they illustrate the attempts of Conservatives to be - as the phrase has it - more Catholic than the Pope. If you listen to the Popes you get a complex and nuanced view of Papal authority; if you listen to Conservatives, too often you do not.