Inflammation, a term coined by the ancients, is widely used in sports medicine. But what is meant when a clinician tells a patient that symptoms are probably due to inflammation? The question of whether inflammation is helpful or harmful to healing can only be answered after inflammation is defined. This brief analysis of inflammation reveals that the term’s definition has changed dramatically since it was first used by Celsus nearly 2000 years ago. The definition also depends on the type of lens the viewer is using—whether it be clinical, cellular, or molecular.