Homonym: hardness (Difficulty)
Hardness is a measure of a material's resistance to deformation, scratching, or indentation. It indicates how well a substance can withstand mechanical forces without changing shape. Different materials exhibit varying levels of hardness, which can be tested using methods like the Mohs scale, where minerals are ranked from 1 (talc) to 10 (diamond).
In practical applications, hardness is important in fields like engineering and manufacturing. For example, steel is often hardened to improve its durability, while softer materials like rubber are used for flexibility. Understanding hardness helps in selecting the right materials for specific tasks and products.