• synonyms


[mee-dee-a-stahy-nuh m]
noun, plural me·di·as·ti·na [mee-dee-a-stahy-nuh] /ˌmi di æˈstaɪ nə/. Anatomy.
  1. a median septum or partition between two parts of an organ, or paired cavities of the body.
  2. 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.
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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 formsme·di·as·ti·nal, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for mediastinum

Historical Examples

  • It has been known to descend along the planes of connective tissue into the mediastinum or into the lungs.

    A System of Practical Medicine By American Authors, Vol. II


  • The subcutaneous tissue, pericardium, mediastinum, and mesenterium contained considerable amounts of fat.


    Thomas Wright Jackson

  • Several lymphatic glands in the anterior part of the mediastinum contained black fluid.

  • This is a point of great practical importance in determining the extension of inflammation into the mediastinum.

British Dictionary definitions for mediastinum


noun plural -na (-nə) anatomy
  1. a membrane between two parts of an organ or cavity such as the pleural tissue between the two lungs
  2. the part of the thoracic cavity that lies between the lungs, containing the heart, trachea, etc
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Derived Formsmediastinal, 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

mediastinum in Medicine


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.interpleural space mediastinal space
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Related formsme′di•as•tinal (-nəl) adj.me′di•as•tinal•ly adv.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.