Anatomy. a hollow, pumplike organ of blood circulation, composed mainly of rhythmically contractile smooth muscle, located in the chest between the lungs and slightly to the left and consisting of four chambers: a right atrium that receives blood returning from the body via the superior and inferior vena cavae, a right ventricle that pumps the blood through the pulmonary artery to the lungs for oxygenation, a left atrium that receives the oxygenated blood via the pulmonary veins and passes it through the mitral valve, and a left ventricle that pumps the oxygenated blood, via the aorta, throughout the body.
Zoology. the homologous structure in other vertebrates, consisting of four chambers in mammals and birds and three chambers in reptiles and amphibians. the analogous contractile structure in invertebrate animals, as the tubular heart of the spider and earthworm.
the center of the total personality, especially with reference to intuition, feeling, or emotion: In your heart you know I'm an honest man.
the center of emotion, especially as contrasted to the head as the center of the intellect: His head told him not to fall in love, but his heart had the final say.
capacity for sympathy; feeling; affection: His heart moved him to help the needy.