egzistencija

1. livelihood; means of living
   Kad je izgubio posao, ostao je bez egzistencije. — When he lost his job, he was left without a livelihood.
   Nove takse ugrožavaju egzistenciju malih firmi. — The new fees threaten the survival of small businesses.
2. formal existence
   Filozofi se pitaju o smislu ljudske egzistencije. — Philosophers wonder about the meaning of human existence.

In everyday speech postojanje is the usual word for 'existence'.