dilatio

Dilatio is a Latin noun meaning enlargement, widening, or dilatation. In medical Latin, it denotes the process or result of widening a passage or orifice. In English medical terminology, the direct Latin noun is rarely used; its concepts are expressed with dilation or dilatation, derived from the same root as the Latin dilatare, “to widen.” The term appears in historical texts and in modern discussions of anatomy and physiology where Latin wording is encountered.

In clinical usage, dilatio refers to the widening of hollow structures such as vessels, ducts, or passages. Common examples include dilatio cervicis uteri (cervical dilation) during labor, and dilatio pupillae (pupillary dilation) in ophthalmology. Dilatation can be physiological, such as the pupil’s response to light, or pathological, as when arteries, cardiac chambers, bile ducts, or other conduits become abnormally widened due to disease, obstruction, or structural weakness. Aneurysms are a form of vascular dilatation, as are certain forms of ductal dilatation seen in imaging studies.

The term also appears in historical and scholarly contexts to describe observed widening in anatomical structures. In contemporary medical writing, however, dilatation and dilation are the preferred terms, with the Latin form retained mainly in historical, linguistic, or specialized philological references. Related terms include dilation (general) and dilatation (medical usage), with cross-linguistic equivalents in other Romance languages.