What does "trisomy 21" mean?

The presence of three copies of the 21st chromosome in the karyotype.

What is a synonym for "trisomy 21"?

Common synonyms include: down syndrome, down's syndrome, mongolianism, mongolism.

noun

noun ·Rare ·Advanced level

Noun

1
The presence of three copies of the 21st chromosome in the karyotype. uncountable
2
a congenital disorder caused by having an extra 21st chromosome; results in a flat face and short stature and mental retardation wordnet