Political Rhetoric, 1917

Someone who disagrees when an intellectual™ suggests what they think is a new idea, but is actually an old, bad idea.

First used to describe an opponent of the French Revolution (réactionnaire), it became the Marxist slur for those opposed to communism from the name given to those who fought against the Bolsheviks in the 1917 Russian Revolution. In 20th century politics, it became a term for anyone who opposed change (communism, basically), from any side.