prisezati

1. Croat. to swear; to take an oath
   Vojnici prisežu na vernost otadžbini. — Soldiers swear loyalty to their country.
   Svedoci prisežu da će govoriti istinu. — Witnesses swear to tell the truth.

The verb (like the noun prisega) reads as Croatian in Serbia. In Serbia: zaklinjati se / zakleti se or polagati zakletvu (vojnici polažu zakletvu, svedoci polažu zakletvu). The perfective is priseći (prisegnuti).