What does brittleness mean?
Brittleness is the property of a material that causes it to break, crack, or shatter suddenly when stressed, rather than bending or stretching first. Glass, ceramics, hard candies, and many metals at low temperatures are classic examples: they resist force up to a point, then fail abruptly with little warning. In physics and engineering, brittleness is understood as the opposite of ductility and toughness, which allow a material to deform and absorb energy before fracturing. Beyond the laboratory, the word extends naturally to metaphor: people speak of the brittleness of an overextended economy, a strained marriage, or aging bones weakened by osteoporosis. The term is precise and mostly formal, appearing frequently in scientific writing, journalism, and technical discussion. Its usefulness lies in capturing a distinctive kind of failure — sudden, clean, and often catastrophic — that softer words like fragility do not quite convey.
The tendency of a material to fracture suddenly under stress without significant plastic deformation.
"Tempering reduces the brittleness of hardened steel, making it less prone to cracking."
Primarily used in technical contexts such as materials science, metallurgy, and engineering.
A lack of resilience or robustness in something non-physical, such as a system, relationship, or state of health.
"The report highlighted the brittleness of supply chains exposed by the pandemic."
Figurative extension of the physical sense; common in economics, sociology, and medical writing about bone density.
Extremely rare; brittleness is almost always treated as uncountable, and a plural form would appear only in highly specialized comparative discussions.
"Different alloys exhibit distinct brittlenesses depending on their crystalline structure."
In materials science, brittleness isn't a flaw so much as a trade-off: diamond and glass are both brittle, yet one is the hardest natural substance on Earth.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of brittleness
Brittleness derives from the adjective brittle, which entered Middle English around the fourteenth century, likely from Old English *brytan* ('to break') or a related Germanic root meaning to shatter, cognate with words underlying 'breach' and 'break'. The suffix '-ness' was added to form the abstract noun denoting the quality itself. The word has remained stable in form and sense since its early use, long predating modern materials science but proving perfectly suited to it.
How brittleness is actually used
Brittleness is largely technical or semi-formal in register: common in materials science, metallurgy, geology, and medicine (especially regarding bones), and increasingly used figuratively for fragile social or economic systems. It is an uncountable noun; 'a brittleness' appears only rarely and stylistically.
Easily confused with brittleness
Fragility is a broader everyday term for anything easily damaged, while brittleness specifically describes materials that fracture suddenly rather than bending — in engineering it contrasts directly with ductility and toughness.