anneal

v. t. [ imp. & p. p. Annealed p. pr. & vb. n. Annealing. ] [ OE. anelen to heat, burn, AS. an&unr_;lan; an on + &unr_;lan to burn; also OE. anelen to enamel, prob. influenced by OF. neeler, nieler, to put a black enamel on gold or silver, F. nieller, fr. LL. nigellare to blacken, fr. L. nigellus blackish, dim. of niger black. Cf. Niello, Negro. ] 1. To subject to great heat, and then cool slowly, as glass, cast iron, steel, or other metal, for the purpose of rendering it less brittle; to temper; to toughen. [ 1913 Webster ]

2. To heat, as glass, tiles, or earthenware, in order to fix the colors laid on them. [ 1913 Webster ]