Anneal \uh-NEEL\ , verb;
1. To toughen or temper
2. To heat (glass, earthenware, metals, etc.) to remove or prevent internal stress
3. To free from internal stress by heating and gradually cooling
4. To fuse colors into (a vitreous or metallic surface) by heating
This word comes from Old English onælan ("to set on fire, kindle") from on- + ælan ("on" + "to burn, bake"). Ælan comes from Proto-Germanic *ailan ("probably"), which derives from Proto-Indo-European *ai- ("to burn").
Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Tuesday, April 26
Etymologies come from the Oxford English Dictionary and/or Etymonline.com