1. Someone who believes in a totalitarian state rule by a supreme leader (dictator) who controls everything possible and treats people harshly -- to gain the leader's own success,* to foment an aggressive military nationalism, and to promote a Social Darwinist belief that hard life strengthens the state by weeding out the weak.
2. A lesser authority (corporation, mayor, cop, boss, parent) who legally issues harsh, burdensome, micro-managing, insensitive, or uncaring orders -- especially when they know, or should know, that their goals can be accomplished with more autonomy and much less hardship or distress.
3. A harsh and probably murderous kind of dictator; a "fascist dictator" as opposed to a "benign dictator".
4. If applied unfairly, a parent authority who is doing their job within reason, but their teen either doesn't agree with their agenda (10 PM curfew to help perform well in morning school), or is insincerely asserting their parent to be a harsh disciplinarian, in order to bond socially with friends.
5. If capitalized, is the name of the historic Italian Fascist political party. Benito Mussolini (Il Duce - "The Leader") was the Fascist founder and Prime Minister from 1922 to 1943, who built a cult of personality around himself using false media propaganda that he was always right, killed those relatively few unbrainwashed who opposed him, and unified Italy for an incompetent war to retake much of the old Roman empire. Apologists encapsulated their approval of his social control-freakery in the saying, "Il Duce made the trains run on time".
"fascist" connotates an official form of antisocial behavior, if society is understood to have valid comfort needs not met by a harsh authoritarian work ethic or supervision style.
"fascist" has general application to the misuse of hierarchical power in government, business, and religion, as well as to all other levels of society. As the global population increases, it will continue as one of the future's most important social issues.
"fascist" behavior can be observed in some form in everyday life, but is especially obvious on TV when ordered by right-wing politicians, mean bosses, and greedy corporations. Parents can be both fairly or unfairly labeled, because some parents are minor fascists, yet teens can't always tell what is fascist over-control, from what is just good parenting.
Many folks should have said "fascist", if they misused "nazi" in poor taste, since the latter is properly reserved for genocide and extermination concerns only.
"fascist" is different from "racist", though racists are often fascists as well. But there are several nation-state military examples where the races have worked together to control the population in arguably fascist or at least military styles.
Unwary citizens can be duped by two-faced "cryptofascist" policies. For example, people in a dangerous neighborhood might accept a policy of police searching all houses for weapons. But the real purpose of the searches might be to locate books supporting the political opposition, and to intimidate or arrest people found nearby. Mussolini was the original cryptofascist, because he started his political life as a Socialist, and then turned against his former political friends when he came into power as a Fascist.
"A fascist cop demanded to know where I was going."
"My fascist boss likes to say, 'My way or the highway'."
"My fascist dad won't let me stay out after 10 pm."
"Don't buy stuff from that fascist corporation; they fired employees sickened by handling their toxic waste."
"Chile's Augusto Pinochet was a fascist dictator, who murdered tens of thousands of his own people."
"Fascist Party leader Mussolini became Prime Minister by threatening to make Italy ungovernable."
*Inspired and adapted from a good top level definition by Redeemer The Vengence Taker, Jan 5, 2005. (See FAcist