Definition of "indurate"

The ear, small and shapely, the arch of the foot, the curve in mouth and nostril, even the indurated hand dyed to the orange-tawny of the toucan's bill, a hand telling alike of the halyards and tar-bucket […] all this strangely indicated a lineage in direct contradiction to his lot.

1924, Herman Melville, chapter 2, in Billy Budd‎, London: Constable & Co.

The superficial temporal artery (or arteries) may become exquisitely tender to the touch and visibly indurated.

1970, Oliver Sacks, chapter 1, in Migraine, London: Picador, published 1995, page 15

Oh, no ! it is the curse of revolutionary calamities to indurate the heart — the revolutionary impulse is too swift to admit of a pause at the sight of individual misery — the tempest is too loud to hear the wailings of the wretch that perishes beneath its billows […]

1801, Helen Maria Williams, Sketches of the State of Manners and Opinions in the French ..., Volume 1‎

The afternoon was not particularly warm: our noses and eyes were running; his were dry. He was evidently indurated against natural hardships.

1992, Saul Bellow, “Winter in Tuscany”, in It All Adds Up: From the Dim Past to the Uncertain Future, New York: Viking, published 1994, page 257

Now are they indurate and tough as Pharaoh, and will not bow unto any right way or order.

1528 (originally published, the wording in the quotation is from a later version), William Tyndale, The Obedience of a Christian Man