IPA: /əˈpɒk.ə.lɪp.tɪst/
KK: /əˈpɑː.kə.lɪp.tɪst/
A person who interprets or writes about the end of the world or a major catastrophe, often in a religious or prophetic context.
The apocalyptist shared his visions of the future during the seminar.
Apocalyptist is formed from "apocalypse" (from Greek "apokalypsis", meaning revelation or disclosure) and the suffix "-ist" (meaning one who practices or is concerned with). The term refers to a person who interprets or believes in revelations, particularly those concerning the end of the world.
Think of someone who is focused on 'revelations' ('apokalypsis') about the future or the end times — that's what an apocalyptist does.
No commonly confused words.