See the usage notes about Nazi.
Limbaugh defined the term as "a feminist to whom the most important thing in life is ensuring that as many abortions as possible occur," adding that, "There are fewer than twenty-five known Feminazis in the United States." However, in practice he and others use the term in a much wider context.
Blend of feminist and Nazi, popularized by politically conservative radio personality Rush Limbaugh, who credited his friend Tom Hazlett, a professor of law and economics at George Mason University, with coining the term. However, this term or one similar may have been independently coined earlier.