Europe's taboos are falling away.

Virulent language castigating immigration and Islam is creeping from extremist fringe groups on social media and the dark web into politics.

And it's getting new visibility ahead of the May 23-26 European Parliament elections . Far-right populist parties who promote these themes are expected to make significant inroads.

A forthcoming study shared with The Associated Press shows a dramatic rise in recent years of two concepts in particular: One is "the great replacement," which asserts that Muslim immigrants are replacing European populations. The other is "remigration," or returning immigrants to their native lands in what amounts to a soft-style ethnic cleansing.

The terms remain verboten for mainstream politicians on a continent scarred by the Holocaust. But the Frenchman who coined the terms, Renaud Camus, is now himself a candidate for Europe's legislature.