IPA: /rɪˈbjuːkər/
KK: /rɪˈbjukər/
A person who criticizes or scolds someone for their behavior or actions.
The teacher was a stern rebuker, always pointing out mistakes to help her students improve.
Rebuker → It is formed from "re-" (meaning again) and "buk" (from Old English "bec", meaning to command or to call). The word "rebuker" refers to someone who calls someone back or admonishes them again for their actions.
Think of someone who is calling someone back ('re-') to correct them or give them a command ('buk'). This helps you remember that a rebuker is someone who admonishes or reprimands.