from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The condition of having three copies of a given chromosome in each somatic cell rather than the normal number of two.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The presence of three copies, instead of the normal two, of a particular chromosome of in an organism.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. chrosomal abnormality in which there is one more than the normal number of chromosomes in a cell
tri- + -som(e)3 + -y2.(American Heritage® Dictionary of the English Language, Fourth Edition)
From trisome + -y. (Wiktionary)