pleural effusion

This term is a precise medical diagnosis used primarily in clinical settings, such as radiology reports or cardiology consultations. It describes a pathological state rather than a disease itself, as the fluid accumulation is typically a symptom of an underlying condition like heart failure, pneumonia, or malignancy.

In a clinical context, the term is often paired with descriptors such as transudative or exudative to specify the nature of the fluid. Because it refers to a specific medical condition, it is treated as a countable noun when referring to individual cases or occurrences in different patients.