Anneal is a verb that means to harden or strengthen.

Our word of the day has evolved from Old English and meant ‘to burn or bake.’ It usually describes a process that involved heating something up, then letting it cool down for the sake of having it harden.

In time, the word simply came to refer to the process of letting something harden. For example: I hope to anneal the posts on my children’s bunk beds. Having posts that aren’t sufficiently strong can be dangerous.