hardness

Everyday

1. Hardness is how hard something is: how well it resists being scratched, dented or pressed. tree →
2. Hardness of water means how many minerals, like calcium, are dissolved in it. tree →
3. Hardness can mean being harsh or unkind (hardness of heart). tree →

In the lessons

In science lessons on materials, pupils test hardness by scratching materials with a fingernail, a coin or a nail; diamond is the hardest natural material. Geologists use the Mohs scale, from talc (1, softest) to diamond (10, hardest). Hard water leaves white limescale in kettles. In stories, hardness of a character means they seem cold and unkind.

Examples

• We tested the hardness of different rocks by scratching them. tree →
• Diamond has the greatest hardness of any natural material. tree →
• The hardness of the wood made it difficult to hammer a nail in. tree →
• Talc is at the bottom of the hardness scale. tree →
• Hard water leaves white marks in the kettle. tree →
• The hardness in his voice surprised her. tree →

Note

Uncountable noun from «hard» + -ness. Hardness is not the same as strength: glass is hard but breaks easily (it is brittle). On the Mohs scale a higher number means harder; each material scratches those with lower numbers.

In Jewish tradition

In Lamentations it means a stubborn, closed heart given as a curse.

Interpretation. In Sefer Yetzirah the double letters, which can be hard or soft, stand for opposites such as softness and hardness, strength and weakness.

Examples

• The [33] seven double letters, בגד כפרת with a duplicity of pronunciation, aspirated and unaspirated, namely: ,תּת ,רּר ,פּפ ,כּכ ,דּד ,גּג ,בּב serve as a model of softness and hardness, strength and weakness. (Sefer Yetzirah, Kalisch 1877) tree →
• Thou wilt give them hardness of heart, Thy curse unto them. (Writings LAM.3.65, JPS 1917) tree →

Note

Uncountable noun from «hard» + -ness. Hardness is not the same as strength: glass is hard but breaks easily (it is brittle). On the Mohs scale a higher number means harder; each material scratches those with lower numbers.