Definition of "cantle"

See how this river comes me cranking in, / And cuts me from the best of all my land / A huge half-moon, a monstrous cantle out.

c. 1597 (date written), William Shakespeare, “The First Part of Henry the Fourth, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, (please specify the act number in uppercase Roman numerals, and the scene number in lowercase Roman numerals)

Their armors forged were of metal frail; / On every side thereof huge cantles flies; / The land was strewed all with plate and mail, / That on the earth, on that their warm blood lies.

1600, Edward Fairfax (tr.), The Jerusalem Delivered of Tasso, Book VI, xlviii

In one cantle of his law.

1644, J[ohn] M[ilton], The Doctrine or Discipline of Divorce: […], 2nd edition, London: [s.n.], book

He recognised a horse when he saw one, and could do more than fill a cantle.

1888, Rudyard Kipling, “The Arrest of Lieutenant Golightly”, in Plain Tales from the Hills, Folio, published 2005, page 93

Next day, he returned with a camel-saddle of equal beauty, the long brass horns of its cantles adorned with exquisite old Yemeni engraving.

1926, T. E. Lawrence, Seven Pillars of Wisdom

The traps were packed in the splitwillow basket that his father wore with the shoulderstraps loosed so that the bottom of the basket carried on the cantle of the saddle behind him.

1994, Cormac McCarthy, The Crossing