IPA: /ˈflɒsər/
KK: /ˈflɔsər/
A tool or device used to clean between teeth by using dental floss.
I use a flosser every night to keep my teeth healthy.
Flosser is formed from "floss" (from Middle English *flos*, meaning a thread or filament) and the suffix "-er" (meaning a person who). A flosser is a person or tool that uses floss to clean between teeth.
Think of someone using a 'thread' ('floss') to clean their teeth — that's what a flosser does.