This is the 826th most frequent Bulgarian word.
енергиен
The Bulgarian word "енергиен" translates to "energy-related" or "energetic" in English.
The word 'енергиен' ('energy') is used here as an adjective describing the 'sector', specifying its relation to energy.
Енергийният сектор играе ключова роля в икономиката.
The energy sector plays a key role in the economy.
Here, 'енергийна' ('energy') modifies 'efficiency', indicating the efficiency pertains to energy consumption or use.
Търсим нови начини за подобряване на енергийната ефективност.
We are searching for new ways to improve energy efficiency.
In this case, 'енергийни' ('energy') relates to 'markets', signifying that the markets are associated with energy production or trade.