This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
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n. The act or process of becoming hard or harder.

n. Something that hardens, as a substance added to iron to yield steel.

n. Gradual exposure of plants to cold weather.

v. Present participle of harden.

n. The process by which something hardens.

n. That which hardens, such as a material used for converting the surface of iron into steel.

n. Making hard or harder.

n. That which hardens, as a material used for converting the surface of iron into steel.

n. the process of becoming hard or solid by cooling or drying or crystallization

n. abnormal hardening or thickening of tissue

n. the act of making something harder (firmer or tighter or more compact)

"“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.”"

harden   

gardening    pardoning