Perioúsios (περιούσιος) means one's own special possession, peculiar, chosen as treasured property. In the LXX, it translates Hebrew segullah — a prized personal treasure.
Titus 2:14: Christ 'gave himself for us to redeem us from all wickedness and to purify for himself a people that are his very own.' The background is Exodus 19:5: 'you will be my treasured possession out of all nations.' Through Christ, this identity extends to all believers. The church is not merely a religious organization but God's prized possession — people bought at infinite cost. This identity produces holiness: 'eager to do what is good.' We live as befits those treasured by God.