The service due to the English crown as the condition of holding land.(noun)
The Century Dictionary (Public Domain)
Use "knight-service" in a sentence
"A minor could succeed to a title but could not administer the associated estates, especially if they were held as "knight-service," until he or she came of age. 28 Hence, the practice of wardship whereby an underage heir became the ward of the crown with their estates reverting to the crown during the heir's minority."
"Even if a minor did not hold lands in knight-service, his or her legal title was a vexed question."
"Hugh Beringar, torn two ways, had delegated the pursuit of the traitors to his sergeants, while he rode at once to the castle to send out the call to the knight-service of the shire to be ready to join the force which King Stephen would certainly be raising to besiege Lincoln, to begin commandeering mounts enough for his force, and see that all that was needed in the armoury was in good order."