Which medical term describes a condition involving inflammation of the heart's lining?

The term that describes a condition involving inflammation of the heart's lining is endocarditis. This specific condition refers to the inflammation of the endocardium, which is the inner layer of tissue that lines the heart chambers and valves. Infections, usually caused by bacteria, can lead to endocarditis and result in various symptoms and complications, making it a serious medical condition that requires prompt treatment.

Myocarditis pertains to inflammation of the heart muscle itself, while pericarditis refers to inflammation of the pericardium, the outer lining surrounding the heart. Angina is not an inflammatory condition but rather a term used to describe chest pain resulting from insufficient blood flow to the heart muscle, often due to coronary artery disease. Thus, endocarditis is specifically linked to inflammation of the heart's inner lining, distinguishing it from the other choices presented.