big fan of Griffin's definition but i'm wondering how uniformly that/other definitions are used.
Fascism is a disputed term and there is a rich literature surrounding it.Most historians would very well scoff at the dilettante who merely speaks of fascism as a "far-right" ideology, as though it is merely arrived at through some shuffling down the political spectrum, however there is much yet to be resolved.
Among historians I think it would be safe to identify a number of points which are largely undisputed about fascism. Namely it is characterized by some recurring themes like opposition to Marxism, Liberalism, and Anarchism, the nationalistic and authoritarian character of its ideology, it's mythic elements, and so on. Listing such things is not my aim here though. In fact I want to discuss how such things have been discussed by historians. For some, these items which I just listed might be safely regarded as 'agreed upon' historical conclusions regarding Fascism. However for the sake of this response I would like to focus on issues of disagreement about what fascism is to respond to your question.
You don't need to browse scholarly literature on fascism long to identify the disagreement that surrounds the term. Allardyce wrote a paper titled "What Fascism is not: thoughts on the deflation of a concept." And I think contained in that title is a bit of a telling story worth keeping in mind. It emphasizes what I regard to be a noteworthy dichotomy in thought about fascism.
One can find those thinkers who seek to extend the term and encompass more movements under the label. They will look beyond where the term was born in Italy to Germany, and Franco's Spain, and Eastern Europe, or even South America. Such thinkers will speak of proto-fascism preceding Mussolini and of fascism in our age. Paxton, Kitsikis, Ernst Nolte, Emilio Gentile, and Griffin give definitional accounts with either necessary and or sufficient conditions which stress certain ideological characteristics specific to fascism, which are commonly cited. In each instance various facets are emphasized to varying degrees and a constellation of characteristics is mapped out in an attempt to create a convincing illustration that maps onto the fascist movements in question.
Others however stress the particularity of fascism as expressive of a very particular historical moment, and thus to export the term beyond the mid twentieth century would be to distort and devalue the term rendering it less specific and robbing it of its descriptive value. They might quibble over claims that Franco presided over a fascist state for instance. Some even insist upon separating National Socialism from Italian Fascism. As intellectual movements it is true that their genealogy was often very distinct, and when answering the question "What is Fascism" it may be suspected that what is being asked may not even be agreed upon.
This of course is even somewhat cursory. The historians and commentators I mention above are few. Hell, everyone and their mother has had a say on the issue, by which I mean to say, often bridging disciplines, philosophers for instance enter into the historical discourse on fascism. This further swells the relevant literature on the subject.
If you are interested in the intellectual relation between philosophy and history and what these disciplines have to say about fascism I recommend secondary literature surrounding the Italian Avant Garde figures like Marinetti and D'Annunzio, and German thinkers like Oswald Spengler, Carl Schmitt, Martin Heidegger, Ernst Junger, and Friedrich Nietzsche. I list these thinkers in the same breath with a cautionary warning- I do not intend to apply the label 'fascist' to them, however I think when discussing an intellectual movement and how it is regarded, it is worth noting those intellectuals who are disputed to have contributed to the movement in question. The debates now over Heidegger and Nietzsche are down right fascinating. An account of fascism is revealed in all those texts concerned with determining whether "Heidegger was a fascist" or whether "fascism was nietzschean" and so on and so forth. Implicit in each accusation and or defense is a definition for fascism, which I would argue is relevant to this discussion.
Tl;dr there is a lot of disagreement about fascism
Check out this thread: https://www.reddit.com/r/AskHistorians/comments/22ox1w/what_is_fascism/