noun

• (historical) A young servant or follower; a trained military attendant in service of a lord.
  "Not all knights held fiefs, and it was not unusual for knights to buy themselves freedom from the obligations of the fief, or even to abscond with the arms provided by their lord, becoming a part of the large number of unenfeoffed, wandering knights available for hire […]"
• (historical) A minor nobleman with an honourable military rank who had served as a page and squire.
• (by extension) An armored and mounted warrior of the Middle Ages.
  "King Arthur and the Knights of the Round Table"
• (law, historical) A person obliged to provide knight service in exchange for maintenance of an estate held in knight's fee.

verb

• (transitive) To confer knighthood upon.
  "The king knighted the young squire."
• (chess, transitive) To promote (a pawn) to a knight.