besnilo

1. formal rage; fury
   Besnilo mu se videlo u očima. — Rage could be seen in his eyes.
   Obuzelo ga je besnilo kad je čuo vest. — He was seized with fury when he heard the news.
2. (disease) rabies
   Psa treba vakcinisati protiv besnila. — The dog needs to be vaccinated against rabies.

In everyday speech 'rage' is usually bes (od besa, u napadu besa); besnilo most often means the disease (rabies), and in the sense of 'rage' it sounds literary and expressive.