heart-sac
nounUK /ˈhɑːt sæk/
US /ˈhɑːrt sæk/
The heart-sac is the little bag around your heart that keeps it safe.
The doctor said the heart-sac was healthy and strong.
OTHER MEANINGS
2. The thin, fluid-filled membrane that surrounds and protects the heart.
Fluid inside the heart-sac helps the heart move smoothly.
3. A protective pouch-like structure enclosing a bodily organ.
The heart-sac is one example of a sac that guards an organ.
4. In some animals, a sac near the heart that holds blood or air.
The fish's heart-sac helps keep blood flowing.