Meaning of Down syndrome

Down' syn'drome

Pronunciation: [key]
— Pathol. Pathol.
  1. a genetic disorder, associated with the presence of an extra chromosome 21, characterized by mild to severe mental retardation, weak muscle tone, a low nasal bridge, and epicanthic folds at the eyelids.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.