SKIP TO CONTENT

dilation

Dilation is expansion, usually of an opening such as the pupil. When that happens, your eyes look black and the light comes streaming in. Grab your sunglasses!

The word dilation is the noun form of dilate, "to make wider.” Dilation often refers to what happens when a woman goes into labor, and her cervix dilates to let the baby through. Dilation is also used for writing or speech that expands on a topic. Here’s a dilation: funny thing is that the -ate ending of dilate is not a suffix but part of the word, so it should really be dilatation, but no one says it that way.

Definitions of dilation
  1. noun
    the act of expanding an aperture
    “the dilation of the pupil of the eye”
    synonyms: dilatation
    see moresee less
    types:
    vasodilation
    dilation of blood vessels (especially the arteries)
    mydriasis
    reflex pupillary dilation as a muscle pulls the iris outward; occurs in response to a decrease in light or certain drugs
    type of:
    enlargement, expansion
    the act of increasing (something) in size or volume or quantity or scope
  2. noun
    (mathematics) a transformation that changes the size of a figure but not its shape
    see moresee less
    type of:
    transformation
    (mathematics) a function that changes the position or direction of the axes of a coordinate system
  3. noun
    a lengthy discussion (spoken or written) on a particular topic
    see moresee less
    type of:
    discourse, discussion, treatment
    an extended communication (often interactive) dealing with some particular topic
Word Family
EDITOR’S CHOICE

Test prep from the experts

Boost your test score with programs developed by Vocabulary.com’s experts.

  • Proven methods: Learn faster, remember longer with our scientific approach.
  • Personalized plan: We customize your experience to maximize your learning.
  • Strategic studying: Focus on the words that are most crucial for success.

SAT/PSAT

$29.95
  • Number of words: 500+
  • Duration: 8 weeks or less
  • Time: 1 hour / week

TOEFL

$29.95
  • Number of words: 500+
  • Duration: 10 weeks or less
  • Time: 1 hour / week

ACT

$29.95
  • Number of words: 700+
  • Duration: 10 weeks
  • Time: 1 hour / week