nesrećan

1. (of a person) unhappy
   Bila je nesrećna u tom braku. — She was unhappy in that marriage.
   Zašto izgledaš tako nesrećno? — Why do you look so unhappy?
2. (of an event) unfortunate; unlucky
   Poginuo je u nesrećnom slučaju. — He died in an accident.
   To je bila nesrećna ljubav. — It was an unhappy love affair.
3. colloq. (before a noun) poor; wretched; blasted
   Opet se pokvario taj nesrećni auto! — That blasted car has broken down again!

Nesrećan slučaj is the fixed phrase for "an accident".