IPA: /ˈsiːtˌbɛlt/
KK: /ˈsitˌbɛlt/
A safety strap in a vehicle that holds a person in their seat to prevent injury during a crash.
Make sure to fasten your seatbelt before starting the car.
Seatbelt → It is formed from "seat" (from Old English *sæte*, meaning a place to sit) and "belt" (from Old English *bælt*, meaning a band or strap). The word "seatbelt" refers to a strap that secures a person in a seat.
Think of a 'place to sit' ('seat') being secured by a 'strap' ('belt') — that's what a seatbelt does.