priseban

1. composed; calm; level-headed
   Ostala je prisebna i odmah pozvala hitnu pomoć. — She kept her head and called an ambulance right away.
   U krizi je potreban neko priseban. — In a crisis you need someone level-headed.
2. conscious; lucid
   Posle udarca nije bio sasvim priseban. — After the blow he wasn't fully lucid.

Often with ostati or biti: ostati priseban means "to keep one's head".