dilatie

Dilatie, or dilation, is the process by which something becomes wider, larger, or more open. The term is used in several fields to describe enlargement of a structure, opening, or region, as well as in mathematics to refer to a specific geometric transformation.

In geometry, a dilation is a similarity transformation that enlarges or reduces a figure with respect to a center point C and a scale factor k > 0. Each point P maps to P' on the line CP such that CP' = k·CP. If k > 1 the image is larger; if 0 < k < 1 it is smaller. Dilation preserves straight lines, shapes up to similarity, and angles; areas scale by k^2. It is one of the basic operations that, with translation, rotation and reflection, defines similarity transformations.

In medicine and physiology, dilation refers to widening of an opening or channel. Pupillary dilation (mydriasis) enlarges the pupil and can be produced naturally by low light or artificially by drugs. Vasodilation is the widening of blood vessels due to smooth muscle relaxation, increasing blood flow. Cervical dilation describes the opening of the cervix during labor or medical examination. Bronchodilation refers to the widening of airways.

In Romanian usage, the noun for dilation is dilatație (or dilatatie without diacritics). Across languages the term encompasses these senses in science, medicine and geometry.