sclerosis

American  

[skli-roh-sis] / sklɪˈroʊ sɪs /

noun

scleroses plural

1. Pathology. a hardening or induration of a tissue or part, or an increase of connective tissue or the like at the expense of more active tissue.

2. Botany. a hardening of a tissue or cell wall by thickening or lignification.

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sclerosis British  

/ sklɪəˈrəʊsɪs /

noun

1. pathol a hardening or thickening of organs, tissues, or vessels from chronic inflammation, abnormal growth of fibrous tissue, or degeneration of the myelin sheath of nerve fibres, or (esp on the inner walls of arteries) deposition of fatty plaques Compare arteriosclerosis atherosclerosis multiple sclerosis

2. the hardening of a plant cell wall or tissue by the deposition of lignin

3. a debilitating lack of progress or innovation within an institution or organization

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Other Word Forms

• sclerosal
  adjective

Etymology

Origin of sclerosis

1350–1400; Middle English < Medieval Latin < Greek sklḗrōsis hardening. See scler-, -osis

Explanation

Someone is diagnosed with the condition sclerosis when a part of their body becomes unusually hardened. A diet that's too high in cholesterol can cause sclerosis of the arteries. In many cases of sclerosis, the stiffening of tissue in organs, nerves, or arteries happens when it's gradually replaced with harder connective tissue. One of the most common forms of sclerosis is called multiple sclerosis, or MS. In this disorder, nerve cells in the spinal cord and brain are affected. Eventually patients with multiple sclerosis experience lack of coordination, numbness, and other symptoms. The Greek root is skleros, or "hard."

Example Sentences

While studying at-home care, she met Lisa, who has primary progressive multiple sclerosis, and her partner Gary, who cares for her.

From BBC • May 24, 2026

Professor Yoshitaka Nagai, a neurologist and Chair of the Department of Neurology at Kindai University Faculty of Medicine in Osaka, focuses his research on neurodegenerative diseases including Alzheimer's, Parkinson's, and amyotrophic lateral sclerosis.

From Science Daily • May 4, 2026

Going forward, new medicines like giredestrant for breast cancer, fenebrutinib for multiple sclerosis and a drug candidate for Alzheimer’s disease seem key to drive Roche’s top-line growth, they add.

From The Wall Street Journal • Apr. 28, 2026

In 1987, Alan Osmond was diagnosed with multiple sclerosis.

From Los Angeles Times • Apr. 21, 2026

By the time she had turned thirty, prison doctors diagnosed her with multiple sclerosis, intellectual disability, and mental illness related to trauma.

From "Just Mercy" by Bryan Stevenson