dilation

American  

[dahy-ley-shuhn, dih-] / daɪˈleɪ ʃən, dɪ- /

noun

1. the act of dilating; state of being dilated.

2. dilatation.

---

dilation Scientific  

/ dī-lā′shən,dĭ- /

1. The widening or stretching of an opening or a hollow structure in the body.

---

Other Word Forms

• nondilation noun
• overdilation noun
• self-dilation noun

Etymology

Origin of dilation

First recorded in 1590–1600; dilate + -ion

Example Sentences

Caffeine temporarily shrinks blood vessels and less dilation means less visible swelling.

From BBC • Feb. 16, 2026

Not only do we tend to mirror each other’s movements, postures, facial expressions and gestures; we also uncannily sync up our heart rates, blood pressure, pupil dilation and hormonal activity.

From The Wall Street Journal • Jan. 22, 2026

Time itself passes differently at such distances -- a phenomenon known as cosmological time dilation.

From Science Daily • Nov. 7, 2025

For a first-trimester abortion that involves cervical dilation and suction, applying a paracervical block is standard.

From Slate • Sep. 7, 2025

“But not to the physical stimulus; you’re not measuring dilation, for instance. It’ll be to the verbal questions; what we call a flinch reaction.”

From "Do Androids Dream of Electric Sheep?" by Philip K. Dick