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