Definition of "rein"

Let their eyes rove without rein.

1667, John Milton, “Book X”, in Paradise Lost. […], London: […] [Samuel Simmons], […]; republished as Paradise Lost in Ten Books: […], London: Basil Montagu Pickering […], 1873,

He mounts and reins his horse.The spelling has been modernized.

, Homer, “(please specify |book=I to XXIV)”, in Geo[rge] Chapman, transl., The Iliads of Homer Prince of Poets. […], London: […] Nathaniell Butter; The Iliads of Homer, Prince of Poets, […], new edition, volumes (please specify the book number), London: Charles Knight and Co., […], 1843,

Being once chafed, he cannot / Be reined again to temperance.

c. 1608–1609 (date written), William Shakespeare, “The Tragedy of Coriolanus”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act III, scene iii]

After an interval that he judged to have lasted twenty minutes, the bed began to shake with poorly reined sobs.

2001, Jonathan Franzen, The Corrections

She worked each horse at a walk, trot, and then a canter. The horses reined well and executed stops quickly.

2011, Marie Claire Peck, Rocking Horse Ranch, page 40

a man subject to these like imaginations […] hath often the stone imaginarily, before he have it in his reines […].

1603, Michel de Montaigne, chapter 12, in John Florio, transl., The Essayes […], book II, London: […] Val[entine] Simmes for Edward Blount […]

He hath caused the arrows of his quiver to enter into my reins.

1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], Lamentations 3:13

My reins rejoice, when thy lips speak right things.

1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], Proverbs 23:16

I am he which searcheth the reins and hearts.

1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], Revelation 2:23