in ancient Rus’, interest on borrowed money. Initially the word apparently meant an addition of something. The rez was paid monthly, triannually, or yearly and was correspondingly called monthly, triannual, or yearly rez.

The practice of usury, which had become widespread in Kievan Rus’, was limited by Vladimir Monomakh after the uprising of 1113: a usurer lending money whose interest was due three times a year was allowed to receive the interest due as the first two payments and the principal as the third payment. If the usurer received the interest three times, he forfeited the sum originally loaned. This rate of rez was thus apparently 50 percent of the sum loaned.