# hardness

/ˈhɑɹdnəs/ (US) · /hˈɑːdnəs/ (UK)

Source: https://englishreference.com/word/hardness
Updated: 2026-08-08

## Senses

### 1. physical solidity

noun · CEFR B2

the quality of being firm and solid, not soft or easy to bend.

For teachers: the physical quality of being rigid or resistant to pressure; the state of being solid in texture.

- The hardness of the mattress made it difficult for him to sleep comfortably.
- The geologist tested the hardness of the rock sample to determine its mineral composition and structural integrity.

### 2. resistance to scratching

noun · CEFR C1 · Technical

how much a material can resist being scratched or dented.

For teachers: the resistance of a solid material to various kinds of permanent shape change when a force is applied.

- Diamonds are famous for their extreme hardness, as they can scratch almost any other surface.
- Engineers must account for the surface hardness of the alloy to ensure the gears do not wear down prematurely under high friction.

### 3. minerals in water

noun · CEFR C1 · Technical

the amount of minerals, like calcium, found in water.

For teachers: the concentration of dissolved calcium and magnesium salts in water, affecting its reaction with soap.

- High water hardness can cause white scales to build up inside your kettle.
- The technician measured the water hardness in parts per million to determine if a commercial softener was required for the boiler system.

### 4. emotional severity

noun · CEFR C1 · Literary

a quality of being cold, strict, or showing no sympathy.

For teachers: a lack of sensitivity, compassion, or gentleness in a person's character or actions.

- She was surprised by the hardness in his voice when he told her to leave.
- The novel explores the hardness of the protagonist's heart, forged by years of betrayal and social isolation.

## Examples

- The hardness of the diamond makes it perfect for cutting glass.
- Engineers must test the hardness of the steel to ensure it can withstand the pressure of the bridge.
- The Mohs scale provides a qualitative measure of mineral hardness by observing which substances can visibly scratch others under controlled conditions.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.