lučiti

1. (of glands, organisms) to secrete
   Gušterača luči insulin. — The pancreas secretes insulin.
   Ova biljka luči lepljivu tečnost. — This plant secretes a sticky liquid.
2. formal (of concepts, phenomena) to separate; to distinguish
   Treba lučiti bitno od nebitnog. — You need to separate the important from the unimportant.

In the sense 'to distinguish, to separate' the verb is bookish and rare; in Serbia people usually say razlikovati, odvajati, razlučiti.