English Reference
Noun

dilation

n.
C1 Advanced US /ˌdaɪˈɫeɪʃən/ UK /daɪlˈeɪʃən/ di·la·tion UK spelling dilations Mathematics

n.the act of making something larger or wider. In math, it means changing the size of a shape while keeping its shape the same.

n.the process of increasing the size or extent of something. In a mathematical context, it refers to a transformation that scales an object from a fixed point without altering its shape.


SIMPLE

The dilation of the pupil allows more light to enter the eye.

CONTEXTUAL

The architect used a dilation of the original blueprint to create a larger model for the presentation.

COMPLEX

In topology, the dilation of a set by a certain radius involves adding all points within that distance to the original set, effectively expanding its boundary.

The hysteroscopies were much worse than childbirth for me – it was zero dilation to full dilation in no time at all.

The Guardian· 19 Aug 2026

From dilate + -ion, late 16th c.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level C1 · Advanced
Frequency Occasional
Updated