čeljust

1. jaw; jawbone
   Ajkula ima veoma snažne čeljusti. — The shark has very powerful jaws.
   Posle udarca slomio je donju čeljust. — He broke his lower jaw from the blow.
2. (of a tool) jaws
   Čeljusti klešta čvrsto drže žicu. — The jaws of the pliers hold the wire firmly.
3. formal (in plural) jaws; grip
   Grad se našao u čeljustima rata. — The city found itself in the jaws of war.

For a human jaw, everyday speech usually uses "vilica"; "čeljust" is more typical for animals and machines.