Dilaation

Dilaation, usually written as dilatation or dilation, denotes the act of widening or expanding an opening, passage, or structure. The term comes from Latin dilatatio; in American English dilation is common, while British usage often prefers dilatation. The form dilaation is typically considered a misspelling.

In medicine, dilatation describes widening of a body opening: cervical dilatation occurs during labor to allow delivery; pupillary dilatation (mydriasis) enlarges the pupil for examination; dilation of a hollow organ or vessel may be part of physiological responses such as vasodilation (widening of blood vessels) and bronchodilation (widening of the airways).

In geometry and physics, dilation refers to the transformation that scales objects relative to a center point by a certain factor, producing an image that is proportional to the original. In botany and biology, dilatation may describe the expansion of tissues in response to pressure or growth.

The term is widely used in ophthalmology, obstetrics, physiology, and geometry; precise spelling should be chosen according to regional convention. When encountering "Dilaation" in text, it is generally a misspelling of "dilation" or "dilatation."