What is the commonly accepted definition of a Nazi?

In the current conflict between Russia and Ukraine, both sides call the opposite one Nazis.

Many politicians or even parties in the West which are not mainstream are also often called Nazis. The most famous example could be Trump, who is definitely a very controversial person, but definitely can't be compared to a Nazi as known from Germany between 1933 and 1945.

After 1945, the winners of the War, which represented both the capitalist and communist part of the world, agreed to some definition of what is a Nazi. I am wondering if that definition is still valid and how exactly it's defined?