sagnuti

1. (sagnuti se) to bend down; to stoop
   Sagnuo se da podigne ključeve. — He bent down to pick up the keys.
   Sagni se, udarićeš glavu! — Duck, you'll hit your head!
2. (+ acc.) to bow; to bend
   Sagnula je glavu i ćutala. — She bowed her head and said nothing.

The imperfective is "saginjati (se)".