IPA: /ˈrɪm.ləs/
KK: /ˈrɪmləs/
Not having a rim or border around the edge.
She chose rimless glasses for a modern look.
Rimless → It is formed from "rim" (from Old English *rym*, meaning the edge or border of a circular object) and "-less" (meaning without). The word "rimless" describes something that does not have a rim or edge.
Think of something that is 'without' ('-less') an 'edge' or 'border' ('rim') — that's what rimless means.