Down's syn.drome medical HdaJnz.sIn7drEJm, $-droJm n [U] dated or taboo mon.go.li.sm a condition which some people are born with and which means they have lower than average mental ability, a flat face and nose, and sloping eyes 唐氏综合症(先天愚型,脸、鼻扁平,眼歪斜)