načeti

1. (+ acc.) to start; to open; to cut into
   Ko je načeo novi hleb? — Who cut into the new loaf?
   Načeli smo flašu vina još za ručkom. — We opened the bottle of wine back at lunch.
2. (of a topic, question) to broach; to raise
   Na sastanku niko nije hteo da načne to pitanje. — At the meeting nobody wanted to raise that question.
   Načeo si veoma osetljivu temu. — You've broached a very sensitive subject.
3. (of health, strength) to undermine; to impair
   Dugogodišnji stres mu je načeo zdravlje. — Years of stress have undermined his health.

The imperfective counterpart is načinjati.