Scientific Socialism and Marx

What is "Scientific Socialism"?

The usage of the word science by Idealists philosophers seems to me to be problematic. 

"Scientific Socialism" appears to be a commonly used term with Marx and Marxists. 

Yet, I am absolutely, positively, certain that socialists in the 20th century didn't use the term "scientific socialism" with an eye to someone like Feuerbach who said in the introduction to The Essence of Christianity that science is a cognizance of specie.

Even a contemporary of Marx's like the anarchist Michael Bakunin jumps all over Marx and his flock about "scientific socialism". So that makes me wonder if even from the beginning equivocation of science was common within marxists/socialist circles (or at the very least with critics of Marx).

Does this ambiguity around the term science lead to core philosophical problems that erode the entire foundation of the Marxist edifice? Does such ambiguity lead to false interpretations that send critics and their critiques of Marx and communism/socialism in general off in a wrong direction from the get go? 

Its a bit of a stretch on my part but can something simple like ambiguity of a term--in this case science-- lead to violence and repression? 

1. What did Hegel mean when he uses the term science?

2. What did Marx mean by the term "scientific socialism"

3. Is equivocation of the word science common with Marxists?

3.1 Does such an equivocation lead to fundamental philosophical problems that have direct impacts on political actions/tactics