Honorary title awarded for service to a church or state
A knight is a person granted an honorary title of knighthood by a head of state (including the pope) or representative for service to the monarch, the church or the country, especially in a military capacity. . The concept of knighthood may have been inspired by the ancient Greek hippeis (ἱππεῖς) and Roman equites. In the Early Middle Ages in Western Christian Europe, knighthood was conferred upon mounted warriors. During the High Middle Ages, knighthood was considered a class of petty nobility.
https://en.wikipedia.org/wiki/Knight