anneal
Anneal (verb) means to heat something, usually metal, and then cool it slowly to make it less brittle and stronger.
Etymology
From Middle English anelen, onelen, from Old English onǣlan (“to burn, ignite, set fire to, consume, heat, enlighten, incite, inflame, inspire, kindle”), from Proto-Germanic *ana (“on”) + Proto-Germanic *ailijaną (“to burn”), from Proto-Indo-European *h₂eydʰ- (“to burn”). The double-N spelling may have arisen by analogy with Latinate verbs like announce, annex, and annul. The word is related to Old English onāl (“that which is burnt, burning; incense”), Old English āl (“fire, burning”), Icelandic eldur (“fire”), Swedish eld (“fire, flame”), Danish ild (“fire”).