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[mee-dee-a-stahy-nuh m] /ˌmi di æˈstaɪ nəm/
noun, plural mediastina
[mee-dee-a-stahy-nuh] /ˌmi di æˈstaɪ nə/ (Show IPA).
a median septum or partition between two parts of an organ, or paired cavities of the body.
the partition separating the right and left thoracic cavities, formed of the two inner pleural walls, and, in humans, comprising all the viscera of the thorax except the lungs.
Origin of mediastinum
1535-45; < New Latin; compare mediastīnus of middle class, apparently identical with Latin mediast(r)īnus a low-ranking slave, perhaps derivative of medius mid1, though sense and formation unclear
Related forms
mediastinal, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for mediastinum


noun (anatomy) (pl) -na (-nə)
a membrane between two parts of an organ or cavity such as the pleural tissue between the two lungs
the part of the thoracic cavity that lies between the lungs, containing the heart, trachea, etc
Derived Forms
mediastinal, adjective
Word Origin
C16: from medical Latin, neuter of Medieval Latin mediastīnus median, from Latin: low grade of servant, from medius mean
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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mediastinum in Medicine

mediastinum me·di·as·ti·num (mē'dē-ə-stī'nəm)
n. pl. me·di·as·ti·na (-nə)

  1. A septum between two parts of an organ or a cavity.

  2. The region in mammals between the pleural sacs, containing the heart and all of the thoracic viscera except the lungs. Also called interpleural space, mediastinal space.

me'di·as·ti'nal (-nəl) adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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