v. [f. TOUGH a. + -EN5.]
1. trans. To make tough.
1582. Stanyhurst, Æneis, III. (Arb.), 76. O my son Æneas, with Troian destenye toughned.
1703. T. N., City & C. Purchaser, 213. To toughen his Nails that were brittle.
1739. G. Smith, Laboratory (1799), I. II. 69, heading. Method of testing, refining, separating, allaying, and toughening [gold and silver].
1901. F. W. Maitland, Rede Lect., 27. Any scheme better suited to harden and toughen a traditional body of law.
1906. Mem. Abp. Temple, I. 471. The experience of life had toughened the fibre of thought.
2. intr. To become tough.
1707. Mortimer, Husb. (1721), I. 185. Lay them in some Room three or four Weeks or more, that they may cool, give and toughen.
1801. Southey, Thalaba, IX. xxx. Ere the green beauty of their brittle youth Grows brown, and toughens in the summer sun.
Hence Toughened ppl. a., Toughening vbl. sb. and ppl. a.; Toughener, one who or that which toughens.
1876. Encycl. Brit., V. 754/2. *Toughened glass invented.
1894. Chicago Advance, 25 Oct., 118/1. [They] went away … with a toughened propensity to be bad.
1895. C. W. Lyman, in Voice (N. Y.), 5 Dec., 7/2. Recommended as a *toughener of the constitution.
1868. Joynson, Metals, 45. The *toughening of cast-iron.
1869. Sir E. J. Reed, Shipbuilding, xxi. 317. The toughening effect produced on a mass of Steel when it is heated, and plunged into a bath of oil.
1881. Raymond, Mining Gloss., Toughening, refining, as of copper or gold.
