to mock: to make sport of someone, treating them with scorn as an object of ridicule
The word is built from the ordinary Greek verb for "to play," which itself comes from the word for a child. So at its root it pictures making a game of someone, treating a person as a plaything for one's own amusement. In the New Testament that play is never innocent: it is cruel sport, aimed at shaming and degrading its target.
Almost every use falls in the account of Jesus' final hours. Soldiers, rulers, and a curious king each take their turn making sport of him: dressing him in a fake royal robe, kneeling in fake homage, jeering at his claims. The mockery is as much acted out as spoken, a staged performance of contempt. Jesus himself predicts it three times, saying he will be "handed over to be mocked."
The same word carries one further shade. When Herod realizes the magi have slipped away without reporting back, he sees that he has been made a fool of, outwitted at his own game. Here the sense tips from open ridicule toward being tricked, though the underlying idea is the same: someone has been made sport of.
Greek has several near neighbors for scorn. Where a word like ἐκμυκτηρίζω pictures the silent sneer of a curled lip, this word is the active, performed cruelty of making a person your entertainment.