zaključivati

1. to conclude; to infer
   Na osnovu čega to zaključuješ? — What makes you conclude that?
   Ljudi često brzo zaključuju po izgledu. — People often jump to conclusions based on appearance.
2. (of a contract, deal) to conclude; to sign
   Firma svake godine zaključuje nove ugovore sa dobavljačima. — The company signs new contracts with suppliers every year.
3. (of a meeting, session) to close; to bring to an end
   Predsedavajući upravo zaključuje sednicu. — The chair is just closing the session.
4. (of school grades) to give final grades
   Profesori ove nedelje zaključuju ocene. — The teachers are giving final grades this week.

The perfective is zaključiti; do not confuse with zaključavati "to lock".