What does anneal mean?
The definition of anneal
An*neal”, v. t.
[imp. & p. p. Annealed; p. pr. & vb. n. Annealing.]
Etym: [OE. anelen to heat, burn, AS. an; an on + 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.
2 To heat, as glass, tiles, or earthenware, in order to fix the colors laid on them.