Also found in: Thesaurus, Medical, Encyclopedia.


 (trī-sō′mē, trī′sō′-)
n. pl. tri·so·mies
The condition of having three copies of a given chromosome in each somatic cell rather than the normal number of two.

[tri- + -som(e) + -y.]

tri′some′ n.
tri·so′mic adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Biology) a chromosome occurring three times (rather than twice) in a cell
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in periodicals archive ?
She became involved with the foundation after she gave birth to a baby girl in 2004 with a disease called Trisome 18.
Regular stalwarts such as the Association of Dutch Oil and Gas Suppliers (IRO), Association of Singapore Marine Industries (ASMI), China Petroleum Technology and Development Corporation (CPTDC), Damen Shipyards Gorinchem, Franklin, Gazprom, Gaylin, JD Neuhaus, Keppel FELS, Kwong Soon, MTQ, Sea & Land Technologies and Trisome will be accompanied by contingent of first-time exhibitors, including Alfagomma, Fujikin, Hagemeyer, Jebsen & Jessen, the Korean International Trade Association (KITA), ST Teleport, Tanken, the World Trade Centre Taichung (WTCT) and many more.
In real life, Kate is a trained therapist with a 14-year-old daughter, Rosie, who suffers from Trisome 9P - a complex learning disability which leaves her unable to speak.