ab·o·li·tion·ist [àbb? lísh’nist] (plural ab·o·li·tion·ists) noun 1. Ab·o·li·tion·ist (plural Ab·o·li·tion·ists) opponent of slavery: an antislavery campaigner in the 18th and 19th centuries 2. somebody who seeks to ban something: a supporter of the abolition of something -ab·o·li·tion·ism, noun