from
The Collaborative International Dictionary of English v.0.48
Pericardium \Per`i*car"di*um\, n. [NL., fr. Gr. perika`rdion,
fr. perika`rdios about or near the heart; peri` about +
kardi`a heart.] (Anat.)
The double baglike fold of serous membrane which incloses the
heart.
[1913 Webster]
Note: The inner layer is closely adherent to the outer
surface of the heart, and is called the cardiac
pericardium. The outer layer loosely incloses the heart
and the adherent inner layer, and is called the
parietal pericardium. At the base of the heart the two
layers are continuous, and form a narrow closed cavity
filled with fluid, in which the pulsations of the heart
cause little friction.
[1913 Webster]