IPA: /ˌæn.ti.əˈbɔːr.ʃən.ɪst/
KK: /ˌæntiəˈbɔːrʃənɪst/
A person who is against the practice or legalization of ending a pregnancy.
The antiabortionist spoke passionately at the rally about protecting unborn lives.
Antiabortionist → It is formed from "anti-" (meaning against) and "abortion" (from Latin "abortio", meaning to miscarry or to bring forth prematurely) and the suffix "-ist" (meaning a person who practices or is concerned with). The word describes a person who is against abortion.
Think of someone who is 'against' ('anti-') the act of 'miscarrying' or 'prematurely bringing forth' ('abortio') — that's what an antiabortionist is.