opsovati

1. (+ acc.) to swear at
   Vozač ga je opsovao kroz prozor. — The driver swore at him through the window.
   Opsovala je komšiju i zalupila vrata. — She swore at the neighbour and slammed the door.
2. (without object) to curse; to swear
   Udario je prst i glasno opsovao. — He stubbed his toe and cursed loudly.

The imperfective is "psovati"; often in the phrase "opsovati nekome majku".