Definitions:
(in the middle ages) a man who served his sovereign or lord as a mounted soldier in armour.

(in the uk) a man awarded a non-hereditary title by the sovereign in recognition of merit or service and entitled to use the honorific ‘sir’ in front of his name.

a chess piece, typically with its top shaped like a horse's head, that moves by jumping to the opposite corner of a rectangle two squares by three. each player starts the game with two knights.

invest (someone) with the title of knight