jedanput

1. once; one time
   Idem na trening jedanput nedeljno. — I go to training once a week.
   Bio sam u Parizu samo jedanput. — I've only been to Paris once.
2. once; one day
   Jedanput smo se slučajno sreli u gradu. — Once we ran into each other in town.
   Jedanput ću ti sve ispričati. — One day I'll tell you everything.

In everyday speech "jednom" is more frequent; it is also written as two words, "jedan put".