What is abolitionism?

Abolitionism was a movement to do away with slavery, notably in the US from 1800 to 1863. Actual slavery in the US was outlawed by the 13th Amendment in 1865.

As a schism developed in the early 19th century regarding the morality of slavery, those who wanted it stopped (abolished) were called abolitionists. The idea of opposing slavery makes it abolitionism. Most arguments for abolition centered on the premise of the founding of the nation, that all people have an inherent right to personal freedom. European nations began outlawing slavery during the same period. During the US Civil War, Abraham Lincoln's Emancipation Proclamation (1863) was the first document to address an end to slavery.
Additionally, in support of this comprehensive look at abolitionism it can be noted that abolitionists or regular government officials, or voters within a US State had abolished slavery in their respective States long before the Civil War. Vermont and Massachusetts as two examples. Also, in 1862, Lincoln and his supporters and Congress abolished slavery in Washington DC.