Definition of "hardening" []

• The act or process of becoming hard or harder. (noun)
• Something that hardens, as a substance added to iron to yield steel. (noun)
• Gradual exposure of plants to cold weather. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "“It would not be important, even with its location unusual,” she replied, her expression hardening in a manner that made Fandral frown and the other druids stir, “if Elune herself had not revealed to me the dread truth.”"
• "He focused on it, his expression hardening as he recognized what it was."
• "“I did,” Donatra said, her expression hardening, “but my largesse was rebuffed.”"