Emily Dickinson Lexicon

HARD'EN, v.t. [hàrdn.]

1. To make hard or more hard; to make firm or compact; to indurate; as, to harden iron or steel; to harden clay.
2. To confirm in effrontery; to make impudent; as, to harden the face.
3. To make obstinate, unyielding or refractory; as, to harden the neck. Jer. xix.
4. To confirm in wickedness, opposition or enmity; to make obdurate. Why then do ye harden your hearts, as Pharaoh and the Egyptians hardened their hearts? 1 Sam. vi. So God is said to harden the heart, when he withdraws the influences of his Spirit from men, and leaves them to pursue their own corrupt inclinations.
5. To make insensible or unfeeling; as, to harden one against impressions of pity or tenderness.
6. To make firm; to endure with constancy. I would harden myself in sorrow. John vi.
7. To inure; to render firm or less liable to injury, by exposure or use; as, to harden to a climate or to labor.