IPA: /ˈwɔːrˌmʌŋɡər/
KK: /ˈwɔrmˌʌŋɡər/
A person who promotes or encourages the idea of going to war.
The politician was labeled a warmonger for his aggressive stance on foreign policy.
Warmonger is formed from "warm" (from Old English *wyrm*, meaning to be hot or heated) and "monger" (from Old English *mangere*, meaning dealer or trader). The word refers to a person who promotes or advocates for war, essentially a dealer in conflict.
Think of someone who is a 'dealer' ('monger') in 'war' ('warm') — that's why a warmonger is someone who promotes war.