Main Entry: peri·car·di·um

Pronunciation: \-ˈkär-dē-əm\

Function: noun

Inflected Form(s): plural peri·car·dia \-dē-ə\

Etymology: Middle English, from Medieval Latin, from Greek perikardion, neuter of perikardios around the heart, from peri- + kardia heart — more at heart

Date: 15th century

1 : the conical sac of serous membrane that encloses the heart and the roots of the great blood vessels of vertebrates
2 : a cavity or space that contains the heart of an invertebrate and in arthropods is a part of the hemocoel