Down syndrome

noun

variants or Down's syndrome

: a congenital condition characterized especially by developmental delays, usually mild to moderate impairment in cognitive functioning, short stature, upward slanting eyes, a flattened nasal bridge, broad hands with short fingers, decreased muscle tone, and by trisomy of the human chromosome numbered 21

called also trisomy 21

Examples of Down syndrome in a Sentence

Recent Examples on the Web

In addition to chromosomal abnormalities like trisomy 21—an extra copy of chromosome 21 that causes Down syndrome—tests also scan for life-altering diseases stemming from single-gene mutations like sickle cell anemia or cystic fibrosis. —Amanda Gerut, Fortune, 29 Nov. 2025

This, Singleton attests, comes from older sister Ashley, who was born with Down syndrome and has competed as a Special Olympics athlete for much of her life. —Luca Evans, Denver Post, 29 Nov. 2025

Having a child with Down syndrome mattered enormously to us. —David Canfield, HollywoodReporter, 25 Nov. 2025

The cause is personal to Watson, whose aunt has Down syndrome. —Pete Grathoff, Kansas City Star, 21 Nov. 2025

Word History

Etymology

J. L. H. Down †1896 English physician

First Known Use

1961, in the meaning defined above

Rhymes for Down syndrome

• acrosome
• aerodrome
• catacomb
• centrosome
• chromosome
• cytochrome
• hippodrome
• honeycomb
• liposome
• meerschaum
• metronome
• microtome

Kids Definition

Down syndrome

noun

ˈdau̇n-

variants or Down's syndrome

ˈdau̇n(z)-

: a genetic condition characterized especially by developmental delays, by distinctive physical traits (as short stature and upward slanting eyes), and by the presence of three chromosomes numbered 21 in human beings

Etymology

named for J.L.H. Down, 1828–1896, English doctor

Medical Definition

Down syndrome

noun

variants or Down's syndrome

: a congenital condition characterized especially by developmental delays, usually mild to moderate impairment in cognitive functioning, short stature, relatively small head, upward slanting eyes usually with epicanthal folds, flattened nasal bridge, broad hands with short fingers, decreased muscle tone, and by trisomy of the human chromosome numbered 21

called also Down, Down's, trisomy 21