IPA: /ˌɛk.sɪˈkjuː.ʃən.ər/
KK: /ˈɛk.sɪˌkjuː.ʃən.ər/
A person who carries out the death penalty on someone who has been sentenced to die.
The executioner prepared for the difficult task ahead.
Executioner → It is formed from "execute" (from Latin "exsequi", meaning to follow out or carry out) and "-er" (meaning a person who). An executioner is a person who carries out the act of execution.
Think of someone who 'carries out' ('execute') a task — the '-er' just means a person. This helps you remember that an executioner is someone who carries out executions.