What did the term "abolitionism" mean in the US before the Civil War?

For example, u/freedmenspatrol wrote, "For the entire antebellum, abolitionists are a tiny minority of white opinion and often openly reviled in the North. Mobs attacked abolitionist meetings, destroyed abolitionist papers, and they were often treated as basically the scum of the earth."

What then was "abolitionism", and how was it distinguished from restricting its spread, hoping that it would end, and putting it on the path to extinction (wasn't that a Republican phrase of the time?)?