Definition of "dilation" [di•la•tion]

• The act of expanding or the state of being expanded. (noun)
• Medicine See dilatation. (noun)
• A lengthy spoken or written discussion on a topic: "an Edith Whartonesque dilation on a social class steeped in hypocrisy” ( Caroline Seebohm). (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "No, the true source of my morning eye-dilation is the rumor of who may be writing and directing this retelling of the sci-fi/horror classic … David Cronenberg."
• "I saw a talk by an atomic clock guy a few years ago who claimed his group could see time dilation from a height difference on the order of a few meters."
• "In case you might have forgotten what the eye examination plus dilation is like:"