IPA: //ˈslɔːtərər//
KK: /ˈslɔːtərər/
A person who kills animals for food, especially in a professional setting.
The slaughterer prepared the meat for the market.
Slaughterer → It is formed from "slaughter" (from Old English *sleohtre*, meaning the act of killing) and "-er" (meaning a person who). A slaughterer is a person who kills animals for food or other purposes.
Think of someone who performs the act of killing ('slaughter') — the '-er' indicates that this person is doing the action.