I feel like each answer here is wrong and right.

Literally, Nazi was a shortened version of National Socialist, and was the anglicized name for the German party that Adolf Hitler rose to power in.

In the vernacular, Nazi is a somewhat catch all to describe various fractions and identified ideologies which the broad usage I think hurts discourse.

Some people mean in this general way, any racist, or ethnostate advocate could be considered a Nazi, as could any racist or fascist group.

I'm not for any of it, but the fluidity of usage ends up feeling like hyperbole when someone is not a literal Nazi, or doesn't even share Nazi values and beliefs.

When describing our enemies, I think static definition matters, because inaccuracies can be an attack surface to dismantle arguments.