IPA: /ˈbɒtəm.ləs/
KK: /ˈbɑtəmˌlɛs/
Having no bottom or limits; endless or unfathomable.
The ocean seemed bottomless, stretching far beyond the horizon.
Bottomless → It is formed from "bottom" (from Old English "bōtm", meaning the lowest part or base) and "-less" (meaning without). The word "bottomless" describes something that has no bottom or is without an end at the lowest point.
Think of something that is 'without' ('-less') a 'bottom' — that's why bottomless means having no bottom.