As the question of whether some historical figures were or were not fascists is in debate here is a variety of definitions. They vary primarily in the extent to which they aim to described specific similarities with Italian fascism of the 1930s or wider movements of a similar character. For reference and use later.

fascism noun mass noun
1 An authoritarian and nationalistic right-wing system of government and social organization.
View synonyms: authoritarianism, totalitarianism, dictatorship, despotism, autocracy, absolute rule, Nazism, rightism, militarism
1.1(in general use) extreme authoritarian, oppressive, or intolerant views or practices.

https://www.lexico.com/en/definition/fascism

fascism noun
fas·​cism | \ ˈfa-ˌshi-zəm also ˈfa-ˌsi-\ Definition of fascism
1 often capitalized : a political philosophy, movement, or regime (such as that of the Fascisti) that exalts nation and often race above the individual and that stands for a centralized autocratic government headed by a dictatorial leader, severe economic and social regimentation, and forcible suppression of opposition
2 : a tendency toward or actual exercise of strong autocratic or dictatorial control early instances of army fascism and brutality— J. W. Aldridge

https://www.merriam-webster.com/dictionary/fascism

Fascism (/ˈfæʃɪzəm/) is a form of far right-wing, authoritarian ultranationalism[1][2] characterized by dictatorial power, forcible suppression of opposition, and strong regimentation of society and of the economy[3] which came to prominence in early 20th-century Europe.[4] The first fascist movements emerged in Italy during World War I, before spreading to other European countries.[4] Opposed to liberalism, Marxism, and anarchism, fascism is placed on the far-right within the traditional left–right spectrum.[4][5]
…
Fascists believe that liberal democracy is obsolete and regard the complete mobilization of society under a totalitarian one-party state as necessary to prepare a nation for armed conflict and to respond effectively to economic difficulties.[8] Such a state is led by a strong leader—such as a dictator and a martial government composed of the members of the governing fascist party—to forge national unity and maintain a stable and orderly society.[8] Fascism rejects assertions that violence is automatically negative in nature and views political violence, war and imperialism as means that can achieve national rejuvenation.[9][10] Fascists advocate a mixed economy, with the principal goal of achieving autarky (national economic self-sufficiency) through protectionist and interventionist economic policies.[11]

https://en.wikipedia.org/wiki/Fascism

fascism noun [ U ] politics (also Fascism) uk ​ /ˈfæʃ.ɪ.zəm/ us ​ /ˈfæʃ.ɪ.zəm/
​a political system based on a very powerful leader, state control, and being extremely proud of country and race, and in which political opposition is not allowed

https://dictionary.cambridge.org/dictionary/english/fascism

Political scientists have agonised over whether there could be a “fascist minimum”. This would be some set of features that define a political agent, regime or movement as fascist. One feature of fascism, as opposed to the other great modern “isms”, as author Anthony Paxton contends with others, is its ideological fluidity or hybridity. Yet certain things should be ventured, lest this “F-word” degenerates into nothing more than an angry label that every party uses to name their enemies, of whatever political stripe.
Fascisms are political movements that aim to take over the state, destroying liberal institutions like an independent media, and individual rights. But not all movements that aim to do this are fascist. Fascists feel licensed to use fraud (“fake news”, propaganda) and, if need be, force in order to achieve this revolutionary aim. Yet again, not all movements that aim to do this are fascist.
To fascists, all life is kampf
One step further, fascists embrace the view that all life is struggle (kampf) or war: between the strong and the weak, within nations, and between the nations, races or peoples. Politics is a continuation of war by other means. Ideals like equality, tolerance, progress, and pity are the ideological rationalisations of weakness. Many fascists, including leading Nazis, are thus deeply opposed to the values enshrined by the biblical prophets and Christianity, seeing in them (following Nietzsche) the product of a regrettable “slave revolt” against the masters in antiquity. For the fascist, we should embrace hierarchies within nations, based on strength and “selections”, to use a chilling National Socialist word. We should accept differences between peoples — so long as groups, “in essence” different, are kept separated by fences and borders. Many forms of fascism thus base their ideologies on pseudo-biological doctrines concerning race, like the Nazis. But not all fascists are biological essentialists. The cultural specificity and history of a group, nation, or “People” (Volk) might be what is being idealised and fought for.

https://www.abc.net.au/news/2018-08-15/fascism-who-is-a-fascist-anyway/10118114

Political ideology that imposes strict social and economical measures as a method of empowering the government and stripping citizens of rights. This authoritative system of government is usually headed by an absolute dictator who keeps citizens suppressed via acts of violence and strict laws that govern the people. The most noted form of Fascism was implemented under Benito Mussolini and Adolf Hitler, who both stripped citizens of their rights and maintained strict regimes that resulted in the deaths of thousands of humans. Some of the defining characteristics of fascism are: (1) racism, (2) militarism, (3) dictatorship, and (4) destructive nationalistic policies.

http://www.businessdictionary.com/definition/Fascism.html

Fascism, Paxton says, is a dynamic process, rather than a fixed ideology like socialism or communism. There are five steps on Paxton’s road to hell, and not all fascist parties made it past the second step:

• Ideological formation and the creation of a party with quasi-military cadres. Talk of national humiliation, lost vigor, and the failures of liberalism and democracy.
• Entry of the party into national politics. Intimidation of rivals, and planned acts of “redemptive violence” against suspect minorities and radical rivals.
• Arrival in government, often in alliance with conservatives.
• Exercise of power, in concert with institutions and business. The regime expands its control at home: restricting the press and democratic processes, corporatizing business, and collectivizing the people. Abroad, it asserts itself militarily.
• Radicalization or entropy: Some fascists go down in a Götterdämmerung, but most die of boredom.

Elements of Paxton’s early stages appear in the angry populism that is gaining ground in modern Western democracies, especially in hostility toward Muslim immigrants and the austerity measures of the post-2008 eurozone. There are politicians whose parties are of fascist extraction, like the National Front in France, whose Catholic-tinged identity politics can be traced back to proto-fascists like the early 20th century Action Francaise. Some of these politicians and parties, like Norbert Hofer’s Freedom Party in Austria, remain closer to their roots than others, and might merit the name neofascist. Others are doing their best to shed the worst of these associations as they enter mainstream politics; the National Front’s Marine Le Pen, for example, is no longer on speaking terms with her father Jean-Marie, the National Front’s founding ideologue. But only one Western democracy, Greece, has a fascist party like Golden Dawn, which possesses both uniformed street fighters and members of the national parliament. When Europe’s “New Right” leaders are called fascists in suits, it’s an acknowledgment that they are not fully fascist. Real fascists wore uniforms.

https://www.theatlantic.com/politics/archive/2016/12/fascism-populism-presidential-election/510668/

Fascism From Latin: fasces, the bundle of rodswith a projecting axe-head, carried before the consuls as a sign of the state authority of Rome, and adopted as a symbol of social unity (the bundle)under political leadership (the axe).The name was given by Mussolini tothe movement which he led to powerin Italy in 1922, but is now used more widely, to include German *Nazism, and Spanish *falangism, on the basis more of a common *ethos than a common *doctrine. Fascism is characterized by the following features (not all of which need be present in any of its recognized instances): *corporatism; *nationalism; hostility to *democracy, to *egalitarianism, and tot he values of liberal *enlightenment; the cult of the *leader, and admiration for his special qualities; a respect for collective organization, and a love of the symbols associated with it, such as uniforms, parades and army discipline.In Germany the cult of *violence, together with a violent *anti-semitism, were added to these features, with notorious results. The anti-communist and anti-liberal stance of fascis tmovements, together with the loathsomeness of many actual examples, have made the fight against fascism a rallying point for left and liberal causes, so that the label ‘fascist’ may often be applied very loosely, to denote almost any doctrine that conflicts with left-liberal ideology. In this expletive use the term conveys no very clear idea, a fact which perhaps explains its popularity. From the intellectual point of view fascism remains an amalgam of disparate conceptions, often ill-under-stood, often bizarre. It is more notable as a political phenomenon on which diverse intellectual influences converge than as a distinct idea; as apolitical phenomenon, one of its most remarkable features has been the ability to win massive popular support for ideas that are expressly anti-egalitarian(seeReich). Mussolini’s own ideas were derived from a heady mixture of popular science, *Marx, *Sorel and*Nietzsche. He advocated regeneration through conquest and perpetual struggle, and spoke, in speeches seething with sexual imagery, of the need to overcome degeneracy and impotence, to make sacrifices for the nation, and to connect to the great ‘dynamo’ of fascism. Fascists are ‘not republicans, socialists, democrats, conservatives or nationalists. They represent a synthesis of all the negations and the affirmations.’ In other words, the ultimate doctrine contains little that is specific, beyond an appeal to energy and action: it is, one might say, the form of an *ideology, but without specific content (other than can be provided by admiration towards the leader).This perhaps explains some of its appeal; it seemed to make no demand other than those which the individual himself would make had he the energy. It then provided the energy.

The Palgrave MacmillanDictionary of PoliticalThought 3rd edition by Roger Scruton

Ur fascism

• The cult of tradition. “One has only to look at the syllabus of every fascist movement to find the major traditionalist thinkers. The Nazi gnosis was nourished by traditionalist, syncretistic, occult elements.”
• The rejection of modernism. “The Enlightenment, the Age of Reason, is seen as the beginning of modern depravity. In this sense Ur-Fascism can be defined as irrationalism.”
• The cult of action for action’s sake. “Action being beautiful in itself, it must be taken before, or without, any previous reflection. Thinking is a form of emasculation.”
• Disagreement is treason. “The critical spirit makes distinctions, and to distinguish is a sign of modernism. In modern culture the scientific community praises disagreement as a way to improve knowledge.”
• Fear of difference. “The first appeal of a fascist or prematurely fascist movement is an appeal against the intruders. Thus Ur-Fascism is racist by definition.”
• Appeal to social frustration. “One of the most typical features of the historical fascism was the appeal to a frustrated middle class, a class suffering from an economic crisis or feelings of political humiliation, and frightened by the pressure of lower social groups.”
• The obsession with a plot. “The followers must feel besieged. The easiest way to solve the plot is the appeal to xenophobia.”
• The enemy is both strong and weak. “By a continuous shifting of rhetorical focus, the enemies are at the same time too strong and too weak.”
• Pacifism is trafficking with the enemy. “For Ur-Fascism there is no struggle for life but, rather, life is lived for struggle.”
• Contempt for the weak. “Elitism is a typical aspect of any reactionary ideology.”
• Everybody is educated to become a hero. “In Ur-Fascist ideology, heroism is the norm. This cult of heroism is strictly linked with the cult of death.”
• Machismo and weaponry. “Machismo implies both disdain for women and intolerance and condemnation of nonstandard sexual habits, from chastity to homosexuality.”
• Selective populism. “There is in our future a TV or Internet populism, in which the emotional response of a selected group of citizens can be presented and accepted as the Voice of the People.”
• Ur-Fascism speaks Newspeak. “All the Nazi or Fascist schoolbooks made use of an impoverished vocabulary, and an elementary syntax, in order to limit the instruments for complex and critical reasoning.”

Umberto Eco https://www.nybooks.com/articles/1995/06/22/ur-fascism/

“Fascism is a political ideology whose mythic core in its various permutations is a palingenetic form of populist ultra-nationalism.”
The palingenetic core of generic fascist ideology

https://web.archive.org/web/20111120193621/http://ah.brookes.ac.uk/resources/griffin/coreoffascism.pdf

Fascism is a set of ideologies and practices that seeks to place the nation, defined in exclusive biological, cultural, and/or historical terms, above all other sources of loyalty, and to create a mobilized national community. Fascist nationalism is reactionary in that it entails implacable hostility to socialism and feminism, for they are seen as prioritizing class or gender rather than nation. This is why fascism is a movement of the extreme right. Fascism is also a movement of the radical right because the defeat of socialism and feminism and the creation of the mobilized nation are held to depend upon the advent to power of a new elite acting in the name of the people, headed by a charismatic leader, and embodied in a mass, militarized party. Fascists are pushed towards conservatism by common hatred of socialism and feminism, but are prepared to override conservative interests – family, property, religion, the universities, the civil service – where the interests of the nation are considered to require it. Fascist radicalism also derives from a desire to assuage discontent by accepting specific demands of the labour and women’s movements, so long as these demands accord with the national priority. Fascists seek to ensure the harmonization of workers’ and women’s interests with those of the nation by mobilizing them within special sections of the party and/or within a corporate system. Access to these organizations and to the benefits they confer upon members depends on the individual’s national, political, and/or racial characteristics. All aspects of fascist policy are suffused with ultranationalism.

Passmore, Kevin,Fascism: A Very Short Introduction (Oxford University Press, 2002)