strogo

1. (of bans, rules) strictly
   Pušenje je ovde strogo zabranjeno. — Smoking is strictly prohibited here.
   Moraš se strogo pridržavati uputstva. — You have to follow the instructions strictly.
2. (of manner, punishment) sternly; severely; harshly
   Otac ga je strogo pogledao. — His father gave him a stern look.
   Sud je strogo kaznio vozača. — The court punished the driver severely.

Common in set phrases strogo zabranjeno (strictly forbidden), strogo poverljivo (top secret).