smrzavati

1. (of a person, with se) to be freezing; to freeze
   Zatvori prozor, smrzavam se! — Close the window, I'm freezing!
   Na stanici smo se smrzavali pola sata. — We were freezing at the bus stop for half an hour.
2. (of water, with se) to freeze
   Voda se smrzava na nula stepeni. — Water freezes at zero degrees.
3. (of food) to freeze
   Svake jeseni smrzavamo papriku za zimu. — Every autumn we freeze peppers for the winter.

For food in the freezer zamrzavati is more common; the perfective is smrznuti.