The Bulgarian word for hour is
час

Translations for hour and their definitions

час	©
1. n. hour (unit of time)
по це́ли часове́ - over a period of many hours, for a long time
2. n. o'clock
двана́десет часа́ - 12 o'clock
3. n. time, hour (pinpointed instant in the day-night cycle)
Колко е часът? - What is the time?
4. n. (poetic) suitable moment (to undertake something)
настъ́пи заве́тният час - the ultimate/conclusive moment has come
5. n. (education) lesson, class, period