IPA: /ˈbɛltləs/
KK: /ˈbɛltləs/
Not wearing a belt or seatbelt.
He felt uncomfortable in his beltless pants during the long flight.
Beltless → It is formed from "belt" (from Old English "belt", meaning a strip of material worn around the waist) and "-less" (meaning without). The word "beltless" means without a belt.
Think of being 'without' ('-less') a 'belt' — that's what beltless means.