n. pl. per·i·car·di·a (-dē-ə)
The membranous sac filled with serous fluid that encloses the heart and the roots of the aorta and other large blood vessels.
[New Latin, from Greek perikardion, from perikardios, around the heart : peri-, peri- + kardiā, heart; see kerd- in the Appendix of Indo-European roots.]
per′i·cardi·al (-dē-əl), per′i·cardi·ac′ (-dē-ăk′) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.