ekološki

1. ecological; environmental
   Zagađenje vazduha je veliki ekološki problem u gradu. — Air pollution is a big environmental problem in the city.
   Ekološka udruženja organizuju protest u subotu. — Environmental groups are organizing a protest on Saturday.
2. (of food) organic
   Na pijaci kupujem ekološko povrće. — I buy organic vegetables at the market.
3. (of products, technology) environmentally friendly; eco-friendly
   Kupili smo ekološki automobil na struju. — We bought an eco-friendly electric car.

4. ecologically; environmentally
   Trudimo se da živimo ekološki odgovorno. — We try to live in an environmentally responsible way.

For food grown without chemicals the usual Serbian term is organski (organska hrana, organsko povrće); ekološki is less common in that sense and more often means simply 'environmentally friendly'.