trisomy Syllabification: (tri·so·my)Pronunciation: /trīˈsōmē, ˈtrīsō-/Definition of trisomy noun Medicine a condition in which an extra copy of a chromosome is present in the cell nuclei, causing developmental abnormalities. Origin: 1930s: from tri- 'three' + -some3trisomy in other Oxford dictionaries Definition of trisomy in the British & World English dictionary
