# Dilation

Dilation (or dilatation) refers to an enlargement or expansion in bulk or extent, the opposite of contraction. It derives from the Latin dilatare, "to spread wide".

In physiology:

• Pupillary dilation, dilation of the pupil of the eye
• Cervical dilation, the widening of the cervix in childbirth, miscarriage etc.
• Dilation and curettage, the opening of the cervix and surgical removal of the contents of the uterus
• Dilation and evacuation, the dilation of the cervix and evacuation of the contents of the uterus
• Vasodilation, the widening of luminal diameter in blood vessels

In mathematics:

• Dilation (affine geometry), an affine transformation
• Dilation (metric space), a function from a metric space into itself
• Dilation (operator theory), a dilation of an operator on a Hilbert space
• Dilation (morphology), an operation in mathematical morphology
• Scaling (geometry), including:
• Homogeneous dilation (homothety), the scalar multiplication operator on a vector space or affine space
• Inhomogeneous dilation, where scale factors may differ in different directions

In physics:

• Scale invariance, a feature of objects or laws that do not change if length scales (or energy scales) are multiplied by a common factor
• Time dilation, the observation that another's clock is ticking at a slower rate as measured by one's own clock

In metal working:

• Dimensional variation, the variation of physical dimensions in response to application or removal of heat

Read more about Dilation:  Dilate