[ mee-dee-a-stahy-nuhm ]

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.

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 mediusmid1, though sense and formation unclear

Other words from mediastinum

  • me·di·as·ti·nal, adjective

Words Nearby mediastinum Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use mediastinum in a sentence

British Dictionary definitions for mediastinum


/ (ˌmiːdɪəˈstaɪnəm) /

nounplural -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

Origin of mediastinum

C16: from medical Latin, neuter of Medieval Latin mediastīnus median, from Latin: low grade of servant, from medius mean

Derived forms of mediastinum

  • mediastinal, adjective

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