prelaz

1. crossing
   Pređi ulicu samo na pešačkom prelazu. — Only cross the street at the pedestrian crossing.
   Na graničnom prelazu smo čekali dva sata. — We waited two hours at the border crossing.
2. transition; changeover
   Prelaz na novi sistem trajao je mesecima. — The changeover to the new system took months.
   Volim prelaz iz zime u proleće. — I love the transition from winter to spring.

The act of crossing is more often called "prelazak", while "prelaz" usually means the place: pešački, granični, železnički prelaz.