IPA: /ˈbʌtənləs/
KK: /ˈbʌtənləs/
Describing something that does not have any buttons.
The new smartphone model is buttonless, featuring a sleek touch screen instead.
Buttonless → It is formed from "button" (from Old French *bouton*, meaning a small knob or fastener) and "-less" (meaning without). The word "buttonless" describes something that does not have buttons.
Think of something that is 'without' ('-less') a 'small fastener' ('button') — that's why buttonless means lacking buttons.