The Collaborative International Dictionary of English v.0.48:

Anneal \An*neal"\, v. t. [imp. & p. p. Annealed; p. pr. & vb.
   n. Annealing.] [OE. anelen to heat, burn, AS. an?lan; an on
   + ?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]

The Collaborative International Dictionary of English v.0.48:

Annealing \An*neal"ing\, n.
   1. The process used to render glass, iron, etc., less
      brittle, performed by allowing them to cool very gradually
      from a high heat.
      [1913 Webster]

   2. The burning of metallic colors into glass, earthenware,
      etc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

annealing
    n 1: hardening something by heat treatment [syn: annealing,
         tempering]

The Free On-line Dictionary of Computing (30 December 2018):

simulated annealing
annealing

   A technique which can be applied to any minimisation or
   learning process based on successive update steps (either
   random or deterministic) where the update step length is
   proportional to an arbitrarily set parameter which can play
   the role of a temperature.  Then, in analogy with the
   annealing of metals, the temperature is made high in the early
   stages of the process for faster minimisation or learning,
   then is reduced for greater stability.