košnica

1. beehive; hive
   Deda ima dvadeset košnica na selu. — Grandpa has twenty beehives in the village.
   Kancelarija je bila bučna kao košnica. — The office was buzzing like a beehive.

Not to be confused with 'pčelinjak', which means an apiary (a place with many hives), not a single hive.