IPA: /ˈmaʊθˌwɑʃ/
KK: /maʊθwɑʃ/
A liquid used to clean the mouth and freshen breath, often containing antiseptic properties.
After brushing my teeth, I always use mouthwash to keep my breath fresh.
Mouthwash → The word is formed from "mouth" (from Old English *muð*, meaning the opening in the face used for eating and speaking) and "wash" (from Old English *wæscan*, meaning to cleanse with water). Together, these parts describe a liquid used to cleanse the mouth.
Think of cleansing the 'mouth' with a 'wash' — that's what mouthwash is for.