povod

1. reason; cause; grounds
   Nije bilo nikakvog povoda za svađu. — There was no reason at all for a quarrel.
   Ne želim da mu dam povod za sumnju. — I don't want to give him grounds for suspicion.
2. (usually povodom + gen.) occasion
   Povodom rođendana spremili smo mu iznenađenje. — For his birthday we prepared a surprise for him.
   Koji je povod za slavlje? — What's the occasion?

Povod is the immediate trigger of an event, while uzrok is its underlying cause.