To accustom by labor or suffering to endure with constancy; to strengthen; to stiffen; to inure; also, to confirm in wickedness or shame; to make unimpressionable.

To become confirmed or strengthened, in either a good or a bad sense.

cause to accept or become hardened to; habituate; "He was inured to the cold"

To make hard or harder; to make firm or compact; to indurate; as, to harden clay or iron.

To become hard or harder; to acquire solidity, or more compactness; as, mortar hardens by drying.

become hard or harder; "The wax hardened"

harden by reheating and cooling in oil; "temper steel"

To cause a change in the crystal structure of steel that increases its wear resistance and toughness. This is commonly done through quenching the steel when it has reached a specific temperature, the criticial temperature.

Harden is a small lunar impact crater that lies in the eastern part of the interior floor of the Mendeleev walled-plain. It is located on the far side of the Moon, and can not been seen from the Earth except by spacecraft.

make fit; "This trip will season even the hardiest traveller"

Tighten. As in harden up the sheet which means to wind in more on a sheet.