IPA: /ˈpɔɪnt.ləs.li/
KK: /ˈpɔɪntləsli/
In a way that lacks purpose or meaning; without any useful result.
They argued pointlessly for hours without reaching a conclusion.
Pointlessly → It is formed from "point" (from Old French *point*, meaning a sharp end or tip) and "-less" (meaning without). The word "pointlessly" means without point or purpose, indicating something done without a clear aim or reason.
Think of something that is done 'without' ('-less') a 'point' or purpose — that's why it is called pointlessly.