Abolitionism is a political movement centered around ending slavery. Thanks to abolitionism, the Atlantic slave trade, in which kidnapped Central and West Africans were sold as property in Europe and the U.S., finally ended in the 19th century.
Abolitionism is a belief that slavery must end. During the height of the slave trade, many Western countries had economies that depended on the free labor of cruelly enslaved people. Even when the practice of slavery was widespread, there were many people committed to abolitionism. The word has a root meaning "abolish," and it can also be used for the political movement to reform, or abolish, the modern prison system.