Epikathizō combines epi (upon) + kathizō (to sit, sit down). It means to sit upon something — to take a seat on. It appears only once in the NT, in the Triumphal Entry account in Matthew 21:7, where Jesus sits upon the donkey that has been prepared.
The single NT use carries extraordinary weight. Matthew 21:7: "They brought the donkey and the colt and placed their cloaks on them, and Jesus sat on them [epekathisen]." This is the fulfillment of Zechariah 9:9 — the humble King entering His city. The King who sits enthroned in heaven (Psalm 110:1) now epikathizōs on a donkey's back. Enthronement language meets incarnational humility in this single word. The Lord of glory seated on the lowest of beasts — this is the way of the cross, the throne of the kingdom, and the nature of true authority.