Definition of "pericardium" [per•i•car•di•um]

• The membranous sac filled with serous fluid that encloses the heart and the roots of the aorta and other large blood vessels. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Over at Sterne, Tim has recounted a harrowing turn of events that saw him rushed to hospital and diagnosed with Pericardia, an inflammation of the pericardium, which is the lining of the heart."
• "The inhabitants, however, always first drink the water in the pericardium, which is described as being best."
• "The heart is surrounded by a sac called the pericardium."