Down syndrome

American  

Or Down's syndrome

noun

Pathology.

1. a genetic disorder, associated with the presence of an extra chromosome 21, characterized by mild to severe mental impairment, weak muscle tone, shorter stature, and a flattened facial profile.

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Sensitive Note

Down syndrome (or Down's syndrome ) has replaced earlier terms, such as mongolism to refer to the disease and Mongoloid or Mongol to refer to the affected person, all of which are now considered offensive.

Etymology

Origin of Down syndrome

First recorded in 1960–65; after John L. H. Down (1828–96), British physician

Example Sentences

We heard from a mother, Opal Foster, whose 18-year-old son has Down syndrome and lives at home as he strives to become a chef.

From Salon • Apr. 29, 2026

Alistair also takes an interest in the intellectual and developmental disabilities community, writing about the effects of the Covid-19 pandemic and war in Ukraine on people with autism, Down syndrome and other conditions.

From The Wall Street Journal • Feb. 16, 2026

This raises the possibility of an advantage over earlier strategies aimed at strengthening Down syndrome related brain circuits, which would have required action during very narrow windows in pregnancy.

From Science Daily • Dec. 17, 2025

People with Down syndrome have an extra copy of chromosome 21, for example, and Fragile X syndrome results when the FMR1 gene isn’t expressed.

From Los Angeles Times • Dec. 11, 2025

“My brother’s name was Michael. The football cards were his. He was older than me. He had Down syndrome and leukemia, and was real sick, so my parents had me in order to save him.”

From "Because of Mr. Terupt" by Rob Buyea